http://sites.google.com/site/kaphotics/emurng
1) DeSmuME, any revis is fine that has save states and access to the ARM9 memory. I've included the one I used in the first link.
2) Yep, computer time in addition to knowing how fast the emulator runs at. On the DS the game runs at 60 FPS, on your computer it usually will not be exactly 60 FPS, which might make hitting a seed take one more try (30 seconds at best )
3) Codes, for one. Pretty much all of them work. You also have easy access to a save editor to extract PKMs, import wondercards at your own leisure, and what you already said. You pretty much lock into a delay.
4) Yes. Here's a site I put some codes on awhile ago that I used for RNG.
5) See the first link at the top of my post.
6) See the first link at the top of my post.
If you have questions you really should hop into IRC and talk to me or Bond. We don't bite