1. You probably need to give yourself some time to adjust to road bike geometry/position compared to the Sedona. Having said that, advice over the Internet is almost worthless. You should consider taking into a bike shop where someone might be able to give you a quick/cheap bike fit. What is the saddle to bar drop on your new bike?
2. Looks are good, you could also consider Shimano SPD's - simple and cheap
3. Not much
4. Shoudn't affect your riding much.