Proto-Germanic reflex

Would the second *-i- in *timiz have come in by analogy?

The idea of a cranberry morpheme is pretty interesting. That's what happened in Proto-Indo-Iranian, right?

I'm not very familiar with Old Norse. How do you think *timfaðr would have reflexed into Modern Norwegian, Danish, or Swedish?

Probably more or less the same, except with the usual loss of -r and respelling ð as d. Danish and Norwegian also often convert unstressed vowels to e.