Thanks for the link... quite entertaining actually, even if I'm not in complete agreement with his rankings. Can't say I'm liking the "De-Toilet" comments in the MCab piece, but it looks like he took a pretty even shot at everybody.
Also, the "Hebrew Hammer" is the new greatest nickname for a baseball player ever. Ryan Braun continues his total dominance over the fantasy baseball world.
Anyway, onto the keeper league questions....
As for league size, 14 will definitely work, but with that many guys I'd be making a strong push to make sure I only got guys who were serious about staying in a keeper league for several years. If you've got guys that tend to flake out after they get bored with something, they could easily ruin the league for the other guys next year. Maybe you can get a few of the less trustworty or consistant guys to team up and be co-managers, or maybe even sit out as "alternates" for the following seasons. Taking this down to 10 or 12 consistant teams would be better than having 14 and having to find 2-3 new owners every season.
Minor league rosters can pretty much accomidate any league size you want. There's plenty of prospects out there, and finding 50 or so of them is as easy as going to MiLB.com. That being said, it's going to become pretty apparent very quickly which owners are into scouting and digging and which ones are just wasting their time. I may wait until after the newer owners got a year or so under their belt before adding this wrinkle into the game... it's not like you couldn't add this in a later year if you wanted to.