Hi bob,
I don't have a wealth of knowledge, but I'll have a go with the bit I do.
1. Believe they do, but I found ALL native traffic, big or small, communicate in Spanish.
2. Only dealt with Malaga flying club on the ground, they were very helpful and professional, both ground staff and instructors all had good English. ATC will communicate with you in English, but to be honest, in my experience, it has never been very easy to understand.
3. Better get someone else more reged up than me to answer that one, but I can't see why it should be any different - one big happy family now and all that....
4. Was definitely cheaper for me, around £70, 172 wet, but I know Malaga are not the cheapest around.
Hope that helps a little,
Regards
LF