If you are premium, than yes I recommend it.
1. Rarely people do low level RDF. (Roll Tank for endless RDF)
2. If your a tank maybe, other than that no
3. Raids are corrupted with GearScore (Naxx req 5.5k+ GS now my dudes), but you may find some guilds willing to take in new guys and gear them up. As for TBC/Vanilla many people do xmog runs, and some have 60/70 twinks that they use to do daily/weekly raids with to gear up.
Experience here was good as long as you have some friends. Best way is to get in a social guild (not Ohdo **** Ohdo never join it) and meet new people. The more friends you have the wider your range will be to get yourself in raids without you meeting the minimum GS req. As you level there is a lot of ganking, but dw it's usually low GS 80s and unskilled PvPers, so not much of a threat as there are other places to level. PvP is about the same. Battlegrounds are horrid for low GS as all the players gank you first and camo you, however stick with your team and you get get your Wrathful offsets and have a head start in ilvl and GS.
Good luck.