My (perhaps limited) knowledge is that mining in a pool will give you more consistent payouts, as you've got the power of the pool behind you. With solo mining, it's a crap shoot. You could get a block on your own in minutes (so very unlikely) or months, if ever. I decided to join a pool to build up a coin-base. If I ever had super high gh/s, perhaps solo, but I just don't think it's worth it to me.
You got it. Mine in the pool and you're guaranteed a payout.
It's extremely difficult to find a block all by yourself unless you have insane hashing power under your belt. Imagine mining for months and not hitting the jackpot. People use pools because they earn little by little all the time; instead of hoping they eventually hit a block, they'll know they'll hit one as a group and will take a portion of the reward based on how much hashing power they're putting into the pool.
You can attempt to mine solo to claim the reward all on your own. Just don't get discouraged if you don't find one for a while.
not only a while. A year for most of us, except if you have 7500GH/s

Didn't know that! Now solo mining really is out of the question
