What are the effects of salting a thin steak that's grilled on a pan?
Related answer to the question Is it okay to salt beef before or while cooking it?

TL;DR: Salting the steak right before searing does not noticeable affect the tenderness.

Concerning the (semi-) frozen or thawed steak: Is it bad to cook frozen meat without waiting it to be unfrozen?

Since your mentioned steak is quite thin I don't think the semi-frozen steak goes "bad".