2GB up to 8GB
Not much on anything, but that depends on what you are using.
8 MB
With a memory card you have a larger amount of memory on your phone. However much is on the memory card. So more space to hold pics and etc.
200
a psp can hold 64gb card or 34 gb card
1 gig
I'm not sure about how much memory they can hold so if i make a mistake please correct me Grey memory card 50 blocks : 5$ Black memory card 100 blocks: 10$ White memory card 1000 blocks: 20$
about 300 in a 2 gb micro sd card
The R4 doesn't hold memory, it's the MicroSD card that you insert into the R4DS that has storage. It will support MicroSD cards with storage of up to 2GB (non-SDHC).
depends on the size of you SD or SDHC card
If by game memory, you mean saves, I think that will be plenty (game saves are only a couple of KB). However, if it means you'll be playing homebrews or other, then 64 MB might not even hold one game. It's best if you invest in a multi-gigabyte one in that case.
it can hold about 5-10 hours depending on video resolution.