1- Is the feeling that the worshipper is an Imam when rising from bowing considered a change of intention and invalidation of the prayer? 2- Is ablution valid if the hand dries during wiping the head except for one finger with which the wiping was completed?

The cure for obsessive thoughts (waswas) is to ignore them and not pay them any attention. The illusion that afflicts a worshipper, making him imagine that he is leading someone in prayer, does not affect the validity of his prayer. This is not considered a change of intention. As for wiping over the head, it is also valid. Many scholars have permitted women to suffice with wiping over part of the head.