nanoweave is a multiplier to the extra hp gained by ADR shield. It is best used where you aren't in a grenade spammed area. if dealing with explosives or against players with great aim; use resist asc
Depends on the situation. Nanoweave is good when dealing with a lot of other infantry. So if there is a lot of other HAs, LAs, and Infis running around, throw that on. I use the grenades when there is a heavy presence of vehicles and Maxes around. I equip the vehicle grenades that stick to the vehicles and maxes, throw on the grenade belt, and start hunting them. It entirely depends on what is needed at the time, or what you are looking to do. I would invest in both because both can be very useful.
I always use nanoweave, but if you use the resist shield go for grenades, as resist and Nano don't stack.
nanoweave or ASC, almost always. For vehicles or groups of infantry you have the RL, especially since the new masamune destroys infantry with its shotgun mode.
After the shield nerf switched to Nano. Kinda miss having those extra nades at times but prefer remaining alive more.