Could someone please clarify two grammatical rules? There seems to be contradictory information in different books.

1) If the sentence were: "Bob's cell phone is broken, therefore he is unable to make a phone call." Is this sentence correct? I've read that HE cannot refer to BOB, b/c BOB is in its possessive form. Is that true?

2) When there is a coordinating conjunction (i.e. or nor for but yet so, with the exception of AND) following a comma, is this ALWAYS connecting two independent clauses?

Thanks so much!!