I have a few questions to port forwarding and Public IP, it might have been asked before and I already searched the whole topic but still could not find any answer.

1) I recently changed to public IP and my account now has @public.maxis.com.my but how do I know if its public IP. My IP address begins with 121 instead of 14 which I read was public IP.

2) I'm not sure about this but port 80 was opened after changing to public IP, or just a mistake by me. But I'm trying to open port 3074, I tried port forwarding on the router itself and assign Public IP to my computer but it still could not work.

Any suggestions/solutions to my problems?