Well the camera is very good in decent lighting conditions. And takes more than decent photos. And is a very good camera to start up with. From what I can see your interested more in close-up photography so it should work very well well for you. It comes with 2 lenses 14-45mm lens and 40-150mm so it will cover almost all your photographic needs.
If you want to shoot at night you are going to run into quite a few problems with the auto focus (at least that was a problem I ran into), or if you wanna take photos of stars (like star trails) well its not going to work - the noise of it ... is just too much. After ISO 400 the camera kinda loses the quality
As for the 8 MP, are only important if you want to print quite large formats - well larger than A4
It depends pretty much on the price - if its over 300 US dollars, is not really worth it. (thats what I payed for mine 3 years ago, but I got it from a friend). If you have the possibility I would really recommend Canon EOS 550D + 50 mm f1.8 lens, because every lens you buy from now on you can use it with other future bodies.
Well it certainly looks like an excellent camera to me. I think anytime you switch from a point-and-shoot to a dSLR when you have clear talent (which you do), it will improve your photos. For instance;
I went from crap like this: (and more horrible macro shots - yes these are my images and I thought they were amazing at the time -.-)
to stuff like this:
Just because my camera was capable of getting me better shots. I had the potential for better photos but my camera wouldn't allow me to progress past a certain point. It was an advanced point-and-shoot, it was like $400 but still no match for a dSLR.
However - "you can give a pro a cell phone and he'll take incredible shots, but at the same time you could give a n00b thousands of dollars of equipment and he'll continue to take horrid shots."
I didn't improve like that straight away though, it took some learning to get from the first batch of images to the second one: here's some in between examples:
It was better than what I had previously been taking, but it still wasn't very good. I just practiced and practiced and practiced, and I still have a very, very long way to go. I look back at those images in absolute horror, but I am also very thankful for them because they are a visual example of how much I've learned since I got my new camera in May.
So basically it's a healthy balance between the photographer and his equipment. Whether you improve or not is up to you. You have an eye for photography, design, composition, etc - how you use it is up to you. Your equipment may be holding you back, as it was me. I'm not saying I'm better than you or anyone else on this site, or that my photos are "amazing" - they're not. They're okay photos. I'm just giving my personal experience with hopes that it helps you some ^^
And in regards to your specific camera model... Lookie here at the Amazon reviews. Might help you just a little ;D
And I say always keep your eyes open to other cameras, and make sure you're making an investment that you won't want to trash in a few years. You'll want to keep your camera for a good, long time (unless of course you have the budget to upgrade frequently, which if you do, go for it), so you want to make sure you've made a sound investment.
Well. There's my two cents. If you ever need help with photography concepts or opinions I'll help you however you need, and I'll be honest too ^^