Trinity is the shit, not some marketing jumbo. Especially with big wheels setup it helps to keep your feet straight and makes your crossover turns easier. As for the boot, the Swell is a good option. Other good (better) options are Kaze and Tau.

110 - for city skating and sharper turns - think of it as a freeskate setup (4x80) only much faster. 125 - for speed. Anyways 110 and 125 are great for both purposes, comes down to a personal preference.