Hi RJ,
I like your thinking! I can tell you're into this SOM stuff and that's a good thing!
I currently have one active '69 team and a 2007 team. This will make it 2 '69 teams at the same time.
I guess to answer your question, I'd say that there REALLY isn't much maintenance to do other than to check your teams each morning (or at night if you're up that late) and then try to tweak things. It's not so bad "time-wise".
With the 20% penalty to drop add, I try to do as little of that as possible, but I see other teams doing tons of it, so who knows.
The drafting is the longest and most frustrating part of the whole process, but it's also the most fun for lots of people including myself.
Now to your second question...I'm in a keeper league where a creative guy named Paul Wooten started us in the 2001 league and we have moved through the decade with franchise players and keepers. It's been really cool and something I'd be interested in doing again.
The only problem you have is when somebody bails in the middle of everything. We have enough really good players here that I doubt it would happen.
I would be interested in some sort of tournament format where you play 8 seasons in different formats and get points for wins, and bonus pts for playoff appearances and championships, or something like you mentioned.