Canon sells these cameras with different names for the European and American markets.
The Canon 350D is sold in the American market as the Canon Rebel XT.
The Canon 400D is sold in the American market as the Canon Rebel XTi.
With Canon, a smaller number means a better product, so the 1D is better than the 40D, which in turn is better than the 400D. Thus, the 400D is the entry level, the 40D is mid-range and the 1D is the professional model. See Gordon's reviews and videos on both the 40D and 400D. Much information to be found there.
If you're a beginner, the 400D will probably be a good way to start.
You can use a DSLR without the need for live view, because the viewfinder is much better than on a compact. Using the viewfinder is the traditional way.
Welcome and don't be afraid to ask questions.