If you are mining in a pool, you're no longer "Solo Mining" - and unless you have an Application-specific integrated circuit (ASIC), a machine made for SHA-256 cryptography, you can rest assured your chances of receiving any kind of reward for work by mining is next to nil.
The reward only goes to those that successfully mines the block and confirms the transactions - so the first person to do it gets all of the fees. When you mine in a pool, you come together as a community and agree on a set of rules for distributing the reward.
I'm afraid as to your last inquiry fringes on my lack of knowledge on this subject - but I suppose if the different nodes you are connected to have differing transactions, then yes - you would be able to choose which ones of those you'd like to confirm (Probably the ones with higher transaction fees) - but I could be wrong.
If you plan on going into mining I feel this link has invaluable information:
If you are actually interested in the clever proof of work scheme you may find this link particularly interesting:
If you do decide to take up mining, unless you want to spend ludicrous amounts of money to compete with the mining pools already established, I'd suggest you join a mining pool.
Hope I answered your questions and cleared some things up. :)