As for the "exactly as written".. I had a teacher like that, in middle school. He was from the north but did not speak his real dialect, instead he transformed his natural speech into as close to spoken "nynorsk" as he could. He was my teacher in the "Norwegian" class, and the only thing we did in that class was to write in Nynorsk. That was all. We had two sets of notebooks each, we had to write essays in Nynorsk twice a week (thus two notebooks so that we could alternate). Until then I had never had any particular animosity against Nynorsk, but I truly learned to hate it through and through. From him. Only now, untold decades later, have I learned to love it. Reading a book by Jon Fosse (the recent Noble prize winner) right now. In fact what I really like is reading the very old, original form as Aasen created it and Vinje wrote it.

Again, it's not a dialect of bokmål. That would sound like bokmål is actually a spoken language and there are dialects of it. It is not. It's the other way around - bokmål is an attempt to create a written language with common elements for a lot of people, and the same was done for nynorsk - it's just that for bokmål the selection was more from certain city areas in the south, and nynorsk more from dialects elsewhere, but that's actually a too easy description. In my own dialect, which originates very far from where bokmål was created, there are tons of similarities but also tons of differences, and the same can be said for just about every dialect.

When teaching Norwegian to foreigners there's really only one practical way of doing that - use an artificial "spoken" bokmål so that the students can actually match speech to written words. That's just a crutch in order to learn the language (after you're done the real learning starts). That doesn't mean that "spoken" bokmål (or nynorsk for that matter) is real outside the learning institution.