ring game player converting

[umdpoker]

hi everybody. i play at party. i was working my way up the ring game ladder (made it up to 2/4) when i realized i was bored as hell playing ring games. i started off a couple months ago playing 5+1 sng's and did quite well. i think i placed in money approximately 60% of the time, and i really enjoyed it. changing gears when it got shorthanded was fun. of course, then i read everywhere that ring games are where the money is at. so, i tried to chase the money. anyways, i have decided to come back to sng's for a while to kill the boredom. i also think i can make decent money at the same time. so, i have a few questions for the sng experts here:
1)when do sng's start getting difficult? is 10+1 much harder than 5+1? paying 20% in fees is just absurd.
2)what bankroll do you recommend in terms of buy-ins? is 50 enough?
3)what win rate can i expect if i ever attain expert status at 10+1? what about very good, but not expert?
4)is nl or limit more profitable? i have played a few 5+1 nl the last couple days, and the play was just terrible. i suck at nl, but i placed in every tourney i entered.
5)if you have any general advice, please lay it on me. thanks.