1. Sure thing. You can even have a game utilizing both, vertical and horizontal layouts.
2. Yes. I'm not sure which exporters are excluded from the free version, but you can always fall back on exporting your game as an HTML and then manually build it outside of Construct 2 (Phonegap Build will do that for you in less than 5 minutes) or upload it to some place and directly display it in the browser.
3. You mean virtual keys? Simply add some button sprites and equip them with an "on touch" action.