Roman, welcome to the forum!
I am only 8 months into cheese making, so take my answers with a grain of salt -- but I'll take a try at answering your questions:
1) Yes, especially if it is vegetable-based rennet
2) Don't know, but wouldn't think this by itself would be an issue
3) Possible, depending on the mold -- but often the off-flavor will be limited to the rind
Hopefully others with more experience will be along shortly to add to, or correct, my answers!