if you deny specific permissions, there is a chance that apps won't run anymore or you'll encounter random bugs. i'm not saying to not do it, but just be aware of possible consequences.
@all access:
1) works very well for me. sometimes even too many popular songs and not enough obscure / random ****
2) don't know, never used pandora
3) beatles & zeppelin are afaik both only on itunes and it took like 10 years for it. but i don't think there are many more big bands that are missing. but as said before, just upload the music
4) the missing social playlist stuff is very annoying. they'll probably implement it soonish, but until then:
http://www.reddit.com/r/allaccessplaylists/ is helpful. there's also g+ groups that share playlists. atm, that's the only possible way to do this...