I currently have a RAC/ASM with grid setup

Grid home version -
RDBMS database version -
on Linux x86_64 - rhel 5.6

We have been having perf issues and we have narrowed it down to undersized SGA and Oracle not efficiently using the existing SGA.
We have AMM configured on ASM instance and the two RAC instances.

I'm planning to increase the SGA and as well go to Manual memory mangement for both the RAC instances. I understand I have to setup hugepages for this to work.

1. Is it mandatory to have both the ASM and Rac instances to be using AMM
2. If I do configure huge pages for Manual memory mangement to work for the RAC instances, how will it affect the ASM instance which has AMM by default.
3. can i Have both AMM and MMM working together on the same server
4. If there are affects to ASM instance? how critical is it .. I mean is it negligible enough that I can go ahead and setup this configuration.

Thanks for your help.