Alright buddy my $0.02 on some points,
Audio podcast, yes. Video podcast, meh, I would only watch one or the other (for the same episode #) and I prefer audio podcasts personally for my commute.
Call ins, one thing I don't like about other podcasts is that when they do call-ins for general discussion, topics can get disjointed and the conversation can go all over the place. If you do call ins, keep the topic jointed ask a question and then open the lines. But, opening the discussion for anything is good too if it's not too disjointed.
Talk about story of the week, let us vote for our stories of the week prior to the podcast and then have that be a segment on the show. '3KB viewers voted up this story of the week' type of thing. Stories can be submitted through Twitter/Reddit/Facebook etc.
Bring up a segment on what you guys are playing, what you guys are enjoying lately, go in-depth, I want to know why you guys are playing what.
Length: An hour; longer if you get interviews.
Schedule: Weekly is good (no need for more than one a week)
Other: is this strictly gaming? I'd love to hear what movies and comics, etc you guys are reading too. Fuck it, even tabletop games
Just my $0.02.