Yes, you are correct on the MAP port, although it can be any cylinder. 3 is the most convenient as it is AFT and the hose is pointed towards the firewall when it is installed.
Common practice for the oil pressure and fuel pressure senders is on the firewall on the left side (pilot's side). Van makes/provides in the firewall forward kit a 3-port sender holder specifically for this purpose. Run flex hoses from the engine to the senders and don't forget to use restrictors at the engine end of the hose.
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, DAR, A&P, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
EAA Homebuilt Council
Van's East Coast Representative
Mallards Landing, GA (GA04)