I think the earlier advice is good - keep your complaint succinct - you were xx hours delayed due to the multiple mechanical issues along with bad/middle seats and broken IFE and very disappointed by the whole experience along with luggage issue (if you don't get your bag). I'd include mentioning the airport pickup fee since they may cover that as part of goodwill gesture.

The broken IFE on its own should get some comp... I've seen that range all over the place from 5k miles all the way up to 20k. The main thing is the initial 6hr delay, bad seats, and ultimate 14hr late arrival. I'd leave it open and don't ask for anything specific and see what they offer. I'm guessing you'll get a call from a customer service agent to apologize and discuss about this seeing you are a DM/2MM.