I think 2 button vs 3 button is self explanatory.
A lapel is the fabric that runs from the collar to the button-point. In the picture you posted, you are wearing a notch lapel, which is basically the go-to standard on suits. There are also peak lapels (Often used on formal wear/tuxedos or more fashion-oriented suits/less business-oriented), as well as the shawl collar lapel (Which is almost exclusively reserved for tuxedos/dinner-jackets/etc.)
-Google this for more info. Its a layer of fabric/canvas in between suit fabrics that helps for better suit construction/draping/lapel roll, etc. Half canvassing is essentially an additional lining in between fabric layers that runs to about mid-way / half of the suit jacket. Full canvassing is the top-echelon and extends throughout the full suit jacket. Fused would be a lack of any liner. See http://www.askandyaboutclothes.com/forum/showthread.php?86160-Canvas-half-canvas-etc.-explained
for more information.
You're correct in that the shoulder width is too much in the photo you posted. Try sizing down one jacket size to correct this. If the suit pants are too small for that size, usually there is always room for a tailor to let the pants out for a better fit.
As Dewey mentioned, at 6'1" you MAY be better off with a L length jacket. Suit sizing usually runs in S, R, and L (Short, Regular, Long.. respectively). Again its pretty self explanatory, and it is a bit hard to tell from your photo since your hands are in your pockets, but the jacket length seems OK to my eye. The ideal jacket length should fall just long enough to cover your butt in the rear, and if you have your arms down straight, you should be able to curl your hands and have the overall suit jacket length fall somewhere right around your knuckles. Now-a-days the fashion seems to be on the shorter end, and that is OK if that is your preference, but its not timeless and may be dated quickly. Just make sure you dont buy something ridiculously fashion-forward that is extremely short and looks like a women's jacket (Although from your picture you seem fine in that department).
Lastly, in regards to your photo and pants-fitment. I think you are perfectly fine here. You may want to shorten them JUST a hair (although it is not necessary) so you have slightly less break (Break = how much fabric falls/bunches up on top of your shoes at the cuff). This is really just a personal preference. You can have a tailor taper the cuff ever-so-slightly (if that is your preference) for a few bucks, but I wouldn't say its necessary. I prefer a slimmer fit, but I'm also a much slimmer guy.
If you need help with anything else, just post. It's a Sunday and I'm bored on a business trip with absolutely nothing to do. Good luck with your search!