Right:

1. Blocks are hidden and when found they give a 25 btc reward currently (these quantity halfves every 4 years i think). Normally people pool in mines which are a team co-operates to look for this blocks and then share the rewards between them according to how much hasing power they have put into the search of this block. If you solo mine and you are lucky enough to find the block you will have the full reward but this is very unlikely since you will be competing against pools with massive hashing power. Generally solo mining is considered to be useless.

2. Well its not going to be good ofc. If you are planing on mining on a laptop forget about it, they are not prepared to dissipate so much heat, unless its a gaming ready pc like an alienware or something you might have a chance but.. Aniway adding some extra ventilation is always a good thing to do, as wel as monitoring the equipment's temperatures.

3. Depends of your electricity costs and your mining hardware, you should calculate how much it costs you to mine. There are various calculator in the internet that will tell you how much you will mine at current dificulty according to your hashing power.

4. You can buy/sell them from people taking the risk or do it through an exchange which will act as an intermediate in the transaction for a fee.
See mt gox, btc-e amongst others.

5. Well I have never mined but i am quite shure you can.

6. At that hash rate currently you would mine 0.02 bitcoins per 24h, thats $2.51. You will know if its worth it for you, if not you could try mining other alternate cryptocurrencies such as Litecoins which will probably give you a better reward. Also take into consideration that difficulty rises everytime and if BFL starts deliverying its ASICS there will be a huge rise in it that will probably leave all GPU miners out of play.