The strakes are there to produce a vortex yes. I think these were introduced on the 737 to produce extra lift at high AoA an low-ish airpeeds.
A guess at question 2 would be that the T7 has alot of travel in the oleo on the MLG, but also the tilted bogie helps "smooth" out the transition to touchdown.
The 777 is not unusual in it's use of spoilerons and flaperons. Roll contol consists of a single outboad aileron, five spoilerons and a flaperon system.
Hope that helps,