I think the easiest way for you is to join
BitMinter, with his custom userfriendly miner. Just create an account on the website, download the miner and press the
Engine Start button. You can trust this pool, the owned is very available for questions or suggestions.
1. Which mode returns higher BTC? (Should I switch to Proportional mode? Or continue using PPS mode?)
PPS because it's immune against pool hoppers, BitMinter will add this new method reward soon (in a few days).
2. Are there other pools that can return me more than 0.53 BTC / 24hr? (I mine at deepbit simply because most miners are mining in it.)
You can try our pool, 1.1 GHash/s is 5% of our pool so 2.5 BTC/block if you join us. A block is in average 1 500 000 shares so we need 5 days to discover one in average. 30 days / 5 = 6*2.5 = 15 BTC per month. I think you will earn more with the new PPS system.