1. lets say I have a fleet outside africa(where my ally has land forces) wanting to attack land forces of my enemy. I try to attack with one army but he doesn't make it from europe.
Can my ally then attack alone in my name as a result?
2. Can I make a pure naval attack on another fleet? (not attacking a control marker)
You can make a pure naval attack, but there is no cost to the opponent for just refusing to fight. The usual cost to this is that you get a +1 modifier in the ensuing land battle, but if there is no land battle, there is no cost here.