Liam is also a big fan of feeding himself, but not with a spoon. He loves finger foods, and is after everything I ever have (especially coffee cups) anyway, in a attempt to keep giving him his food, I have been using what I call "the distraction technique" where I give him a wooden spoon or a toy or something to play with as I shovel food into his mouth. Without a distraction, he buttons up his lip tight and shakes his head no.
As for the whole milk, Liam is on whole milk, I switched all three of my kids at 9 mos ( all are above average size and we have no food allergies)
If you can, I would try to go right to the sippy cup it makes it an easier transition if you can do it. Nuby makes one with a soft top that Gemma liked, however, Liam likes the hard top ones ( he takes a bottle though)
Good luck and let us know how you make out.
Lisa