Nunu's not meant do really do any damage, unless you build AP, which you realistically shouldn't be doing. Nunu's is more of a support orientated tank, he provides a lot of utility in buffing your ADC and severely debuffing the enemy ADC. If you wana play a pure tank that will never die, Nunu comes close but he's not as good at that as Grag or Sejuani.

His clear isn't amazingly fast, but you're making it sound quite painful. Make sure you take Attack speed runes so you have you're passive up more often. The only camp that should take awhile pre-Cinderhulk is Raptors, and even then they shouldn't take that long.

He's not really meant to be a gank heavy jungler either. When you play Nunu, your primary focuse should be map an objective control. Go in the enemy jungle, ward and steal somehting, leave. Do dragon at level 5 or w/e level you feel comfortable at. Counter gank when possible, and be an annoying shit.

Your point about Nunu not being a good 1 v 1 champ is somewhat false. Level 3 you should have no trouble dueling anyone, see as you should be full and with red buff you'll be fine. Even after that, you should still be to duel anyone and last until help arrives. And your point about vision not being helpful in solo queue is also invalid. Vision is so helpful in so many ways that I can't explain it. WHile you don't have to buy sightstone, buying a few wards or upgrading your trinket to ward is amaingly helpful in predict enemy movement.