Wary fighter on L!Tiki

Yes, the only unit that can use wary fighter qr is normal hector, who breakers every weapon.

Yes, although she could still double in the enemy phase if she has 5 more speed than the enemy if she uses QR. When 2 skill effects clash like this, they cancel each other (either completely or partially) and the game checks for speed.

If you read the description on wary fighter more carefully, you'll notice that both sides will lose a follow-up, so if you want her to follow-up then you need QR, at which point you're turning her specifically into an anti-boldfighter, which she does better with special fighter (on player phase preferably) anyways