The sensors in the T2i and the T3i are the same. Image quality and abilites will be exactly the same. The biggest difference in the T3i is the articulating screen. IMO-that is a recipe for a disaster, but a lot of entry level shooters and possibly video shooters really like them. The t3i has some options for reduced resolution shooting that the T2i doesn't have-which is kind of silly if you ask me. Why buy a high quality camera to reduce the quality of the image you capture? Doesn't make sense. I believe there are a couple of abilities with video that are slightly different too. So, you can save a few bucks by going with the T2i if the few differences aren't MUST NEEDS for you.
Once you move to a DSLR the screen is NOT good for taking images and focusing. You will really need to use the viewfinder (which isn't even present on most point and shoot cameras anymore) to get the best images. So, the screen being a NEED? probably not for most people.
Review on the T3i from CNet
'Choosing between the T3i, T2i, 60D and 7D' - Canon EOS Rebel T3i (with 18-55mm IS II lens) user review and rating - CNET Reviews
Buy the kit lens and if you have the budget to cover it add in the 50mm f/1.8 and here's why: The kit lens is a great entry level lens and has pretty decent quality for a consumer lens, but the widest aperture changes as you use the zoom on it. If you are using manual or learning to use manual that changes your settings if you move the zoom at all. The 50mm isn't a zoom and it doesn't change it's aperture on you unless you change it. That makes it a bit easier to use while you are learning about the exposure triangle.
It is also f/1.8 which is almost two stops more light than 3.5 and 3 stops more light than 5.6. What does that mean? You can shoot in MUCH MUCH less light with it than you can with the kit lens. That's a big deal inside during the winter when you are learning.
It's also a prime lens-no zoom. Primes are the sharpest lenses on the market. It'll give you a good taste for a sharp, prime lens.
It's cheap as hell for it's abilities. I think it's the cheapest lens in the canon line up right now and for a fast (f/1.8) sharp prime it's worth it's price twice over.
Then add the book Understanding Exposure by Bryan Peterson
After that add a decent camera bag that will allow you to keep it all safely stored in one place.
ENJOY!