Eh, it's just DF with a new coat of paint. DF worked by datacenter, so RF was doomed to work by datacenter.
You can't--the game will check to see if you've ever cleared a floor prior to letting you select completion for it.
What will likely happen is beginning/middle/end learning flags are going to be a nightmare. Nobody is going to tick of beginning on A5S after the first, like, week, because nobody is going to want to get stuck in a group wiping on Hummel for a lockout. There's no real division in Ratfinx for middle/end to have much meaning, either. 6 at least divides up nicely--Blaster is beginning, Vortexer is end, but you run the risk of people overestimating how well they have a given robot down. 7 I guess you go by jail sets? 8... I dunno, that fight has a billion phases.
The biggest problem with learning mode is it relies on people both understanding their own competence in a fight, and being able to openly admit it. Could go over great if everyone's responsible? But then you also run into the issue of needing the group to have people capable of explaining things, and having certain key roles covered (it's possible to end up in an experienced or all-cleared a5s group with all the combat roles covered and nobody who has bombs experience.) Which isn't bad, but is where the 90 minute limit will suck.
