We're only supposed to respond to one question, so I will try to help you out with Faber's strengths and weaknesses. First, his strengths: Faber is quite an intelligent man and is able to teach Montag quite a bit, such as why books are feared, etc. He also is good with electronics, which helps because he was able to invent the two-way earpiece and keep in contact with Montag. Finally, although Faber is a self-proclaimed "coward", he is still willing to help fight the "system" to some extent - he agrees to help Montag plant books in firemen's homes, helps Montag escape, etc.
As far as his weaknesses, as was previously mentioned, Faber does call himself a "coward". Aside from this, Faber seems to play the "wise old man" role in the story, so he might only have that single flaw.