1. If I'm starting from lvl1, I get boots with the same % of movement speed or just 1-2% difference. I rather have no movement speed at all in boots than having dsync issues. At 70, I just use Paragon points to make them all have the same % of movement speed.

2. At the beginning yes, even blue items. At 70 yellows and legendaries. Once u have semi decent gear, just legendaries. This can take a while depending on the class. Melees can be very slow and pretty boring. Ranged classes, specially DH are far easier and less frustrating than melee. A single DH with M6 will literally carry your whole team thru T6 without much effort.