I'll try to answer:
1) No you do not need to change the code in the php files.
2) You do not need to do anything with the Incoming or Update Action Set to work with amember.
3) Your applications are not seeing each other.
Is your url correct?
https://applicationname.infusionsoft.com:8447/api/xmlrpc4) Do you have tags set up in your Infusionsoft application for your subscriptions?
Hope that helps.
Deborah
www.infusionsoftconsultants.com