Hi @jmateo!
Let me just give you some small tips on your questions as nobody could answer so far 
I would recommend creating a master-slave assignment for each individual contact!
Splitting surfaces makes sense especially when you need to define a separate boundary condition.
Looks like a good mesh to me. I would start with a coarse mesh always and do a convergence study to see the effect on the results.
Looks good to me so far. You need to define the coordinates as you are using the remote displacement boundary condition. You could also work with a fixed support or a displacement boundary condition setting the lower part encastré. My colleague @rszoeke created a nice post for this issue a while ago: Remote Displacement BC.
Best,
Jousef