Gen_server and Gen_fsm questions

[Casper]

Hi All,

It's me again with a list of questions.

Gen_server:
1) Does gen_server execute code synchronously?
2) Even though gen_server Cast is a asynchronous request, in terms of
Gen_server, it's synchronous code execution, right?
3) So if I need to process things in parallel in the server side, how can I
do it?
4) Then what happens to the Gen_server State, if parallel execution can
happen?

Gen_Fsm:
1) As I can see Gen_fsm starts its own process for each state machine.
2) Because of that if I use Gen_fsm to maintain Call (Telecom switch or PBX
kind of system) handling, for each Call a new process starts.
3) Is this a good method?
4) Or rather should I use an Erlang Dict to have Call Circuit State machines
and update each machine in every call event?

All of above are not questions, some are statements. If you can advice me in
terms of Best Erlang Practice, I really appreciate.

Also I wonder if any of you out there, who has done Telecom platforms in
Erlang, is willing to provide consultation to me.

Thanks in advance!
Eranga