1. You're not going to find a new phat DS, there are all lites now. Your only question is which cool color.
2. Yes. Some of the carts have their own memory and some use microSD cards. It's an esoteric techinical point, but for carts which use micro SD cards, you don't actually load anything to the cart from your PC, you load to the microSD which interacts with the cart. Just being overly anal to try and keep things clear for you.
3. Bigger can be better but some carts don't do SDHC. My R4 runs just fine with a 2G SD. It won't do SDHC.
4. Yes. You can do everything yourself and yes you can ask us questions here. For some topics you may need to go to PM's.
