The whole fullscreen start menu is touchscreen oriented. Scrolling a mousewheel up and down to scroll left and right is ridiculous. Having to go into the corners and "swipe" away from it is definitely a touchscreen gesture, swiping from the left side to switch apps is made for fingers on a screen that has a screen that's flush with the outer bezel, not a mouse.
I don't find scrolling left and right with the mousewheel that ridiculous, really. It's no more ridiculous than using the mouse wheel to zoom or change volume, in my opinion, but to each his own. In any case that's hardly a matter of forcing touchscreen gestures on mouse users, since it's explicity using a mouse-only feature. If scrolling was achieved by dragging the cursor left and right, I'd agree that that's a case of forcing touch gestures onto mouse users, but that's not what's happening.
I don't really understand what you mean with the other ones. I don't swipe from the left to switch apps. I bring up the app list with the hot corner and then drag and drop the app images. I'm not sure how you're doing it based on your description. Also, I have no idea what this swiping away from corners gesture is supposed to achieve, because nothing happens when I try it.