Day Questions

If the imam of the congregational prayer does not possess a body part or it has been cut off, is it permissible to offer prayers behind him?

It is permissible to pray behind him provided that other conditions of the imam of congregational prayer are met.

Is it permitted to do wudhu with mascara on?

If it does not prevent water from reaching the skin, then it is permissible.

At what point can I consider one adil, so to accept him as a witness or in leading the congregational prayers? Is there a certain amount of time I must spend with him, or is it sufficient to spend a short amount of time but to feel generally sure of his adalah?

There is no specific time for this, but it depends on socializing for a usual period that is sufficient for the manifestation of goodness from him and the absence of ill deeds.