4, even 5 preseason games is too many. I think the playoffs schedule is fine but regarding the hall of fame game, that should be the 1st week of the preseason and not just another game in addition. 3 weeks is fine.
I really don't like the idea of extended play offs.
Making the play offs isn't easy and makes it real valuable right now. Having more teams in the play offs will mean more SB winners with 9-7 or 8-8 records. Though my beloved Giants won the SB after a 9-7 record, it doesn't change my view on the overall picture.