I'd expect the F2 to be a better fit for your list. IMO the F6 is too shallow for most longer lenses, like your 70-300 zoom.
As to strapping a monopod onto the bottom, there aren't really any anchor points for that. The front snap rings [i]could[/i] be used for that but then they'd be pulled out of position for the flap closure. There are a set of D rings on the back about 2/3 of the way up., for piggy-backiing a satchel or for attaching the BackPack Strap, that could be used. Unless you've got a very-many-section monopod though, the monopod will be sticking out at both ends when carried horizontally and secured to the bag. The first Domkes included a couple of strips of Velcro on the strap so you could fasten a monopod there. That got dropped pretty early on though you could duplicate it fairly easily if you have a heavy-duty sewing machine (or wanted to get a shoe-repair place to stitch it for you)