The path I would recommend to learn full stack development.

Go through the books Head First HTML and CSS (get an inexpensive hosting account you can FTP files to and setup some domains, point to your hosting), next go through Head First PHP and mySQL. Next is Headfirst Javascript then Headfirst jQuery.

After those you should sign up for teamtreehouse.com.

You could play around with developing this in PHP without a framework, setting up a login in system you would learn a lot. Sometimes frameworks are tough to understand what all the magic is happening behind the scenes if you haven't creating a simple app with login, etc in vanilla PHP on your own. For your customer version though you will want to use a framework, more secure, better organized code, etc.

I would recommend developing this with Laravel(PHP) it has a great community so you'll be able to find great learning resources to get started. (Rails is good too, but I think Laravel will be easier to get started/deploy your app)

Also I recommend developing on a mac. Windows always seems to have obscure issues that you will waste hours/days on.

laracasts.com will get you started with Laravel.

There are great deployment tools forge and envoyer. Hosting on Digital Ocean is perfect for most apps, AWS and linode too)

Use stripe for billing.

There is a SaaS add-on to the framework call Spark. It's ok but, I find I'd rather roll my own stripe/SaaS integration.

Also Spark does use Vue.js though so since you're just learning I would stick with developing the app using jquery for ajax interactions and think about moving up to vue in the future.

I would create the MVP as a web application for all the interactions. Then once you have that established you can look at adding true android and iOS apps. Those might be better to hire out the development of. Or a future learning project.

You should be able to set everything up as a mobile web application, use the bootstrap framework for the look and feel of your app. There are some ready made admin templates that can get you something similar to baremetrics.

Having your Dad's plant as an initial user for your app will be great to refine what they need get their feedback.

Good luck. Follow up and let us know how it's going.

C and C++ aren't the easiest languages to learn given they require manual memory management, so you have it fairly easy learning something else, unless you actually want to use C++ for the backend (I would hesitate a lot to recommend C). The main advantage of using something like PHP/Python/Ruby/Node vs C++ is the nonexistent compile times, along with the fact that they're all much higher level and let you focus on your app's requirements. That said, no language is perfect; it's about picking the one you can live with the easiest. Another potential consideration is to choose a language that a lot of programmers in your area are familiar with, so that you have a competitive market to take advantage of if you need to bring in extra help.

I'd say that it would be significantly easier to not spin this a general-purpose SaaS stack, but instead build this as a bespoke system specific to these plants' requirements. It will make developing the system significantly easier, especially given that this would be your first major project. Practically every enterprise/environment is full of custom applications; these are not unique at all.

(That said, from an educational standpoint, thinking about how you might generalise what you build would be a good idea, and serve you in building similar systems later on.)

Assuming you haven't already done this, what you definitely need is information about exactly what everybody needs to be able to do. You have an absolutely excellent opening with the fact that your Dad owns one of these plants: you should be able to easily get access to wander around your Dad's factory and ask questions of everyone when they have moments of free time. I would strongly recommend having long conversations with the workers themselves and completely hearing out how they would solve the issues they have on the floor. Potentially be prepared for the application to suddenly become very different than what you planned :) - you may end up electronically enabling/adding brand-new functionality to these plants' capacity/capabilities alongside the analytics and number crunching features you initially started out with.

It might be a good idea to do several rounds of questions, as you can discuss things in greater depth as you internalize what you learn and come up with unknowns as you work out how to turn problems into helpful code. You may or may not find asking questions helpful at the point you're at right now. Maybe an idea to discuss with your Dad.

As for an immediate long-term goal to figure out how to reach, I'd suggest taking the architectural requirements you have thus far and going ahead and figuring out how to put together a system that provides those things. This might be an existing system you buy (although I would strongly recommend grabbing some freelance consultant help for an independent go/no-go if you think about this route) or an open-source software stack that you can start with, or a stack you build yourself from scratch.

You may need to go through several iterations of designing, spending long days and nights on building, and then realizing you have to throw away half the system and start again. This is not a bad thing; in fact right now I'm building a crawler for a specific website that I'll use once and throw away. It's gotten to a couple thousand lines of code right now (it's quite simple, but PHP is quite a verbose language for async network stuff, and I'm unfortunately yet to learn a better language like Go or Python), and I'm basically putting it together for this once-off use-case. I've mentally saved a LOT of valuable information about Web crawler design that will go into my next major project, a more general-purpose crawler (note the things about generalization I mentioned earlier). I couldn't get this info from reading tutorials or even academic papers or theory.

Oh, another thing - databases are weird and annoying, but I would highly recommend you learn them in depth. There are lots of choices; MySQL/PostgreSQL are the de-facto relational options (and for MySQL there's phpMyAdmin, which is awesome for mental modeling and simple setup); Cassandra scales out to a staggering level; SQLite3 is great for learning on and prototyping with; MongoDB comes with utterly insecure defaults and doesn't scale well but does kinda work (not dissing it, just being honest). There are many others. Query plan optimization is something that should be absolutely logical but is full of obscure edge cases, and writing the same query with different syntax sometimes gives inexplicable speed boosts. Lots of confusing fun - my point is figure it out to the point where you're comfortable with databases and can easily reason through them.

You probably discovered http://stackoverflow.com/ long ago; if you don't already have an account with a few hundred reputation I would recommend going on there and answering a few questions so your account has enough reputation that you can do things like use chat and such. Some of the other Stack Exchange sites like http://codereview.stackexchange.com/ may also be of help.

Good luck, and I kinda want to hear how this goes :)