Sinalli - I would suggest you research this site as there are tons of "which camera to buy" threads that will offer a variety of opinions. Canon, Nikon, Pentax, Olympus, and Sony are the primary players in the dSLR arena. To address your specific points:
1- At least 10MP resolution - Most current dSLRs are 10-12mp, so this should not be an issue in your search. The 1 camera that you likely will read about that is less than 10mp is the Nikon D40. Many people just love that camera, which is 6mp. That model has been discontinued, but pretty widely available as a used or refurb model.
2- Good range of aperture number - This is a lens issue, not a camera issue.
3- Good range of shutter speed - Most are going to range from bulb (ie - any amount of time) to 1/4000th of a second.
4- Should be SLR - Agreed! Opens up a world of possibilities.
5- Should be full frame (If it's possible)-Please tell me more about this issue - The least expensive full-frame cameras are Sony. You are looking at 2x-3x the cost to move from a crop sensor to a full frame sensor. To learn more about this issue, search "full frame".
6- Has good special effects - Many SLRs have "in camera editing" features such as conversion of a photo to black & white, cropping, red eye reduction, etc. Even entry-level cameras offer this.
7- Has good optical zoom - This is a lens issue, not a camera issue. Unlike point & shoot cameras, SLRs don't have that "digital zoom" feature (you just crop a picture to "zoom" in).
8- I could change its lens - This is a feature of all SLRs.
I happen to have a Nikon D90 and absolutely love it. My son has a Nikon D3000 and he loves it as well (although I personally think that the D3000 has some flaws). Of course, the D90 body is about 2x the cost of the D3000 body, so it would make sense that I feel that way.
Anyhow, in the Nikon line, new models in cost order include: D3000, D5000, D90, D300s, D700, D3, D3s, D3x.
The Canon, Pentax, Olympus, and Sony lines each have 4-6 models as well.
From a cost perspective, $1,000-$1,500 will give you a good amount of flexibility for a body and good lens. Don't forget "extras" such as a nice bag, tripod, etc.
Good luck and have fun shopping! John
