If there are two routes in the routing table to that destination, then it will have a 50/50 shot of going back the same way. The router isn't going keep state for which interface the traffic flow is coming in and going on, it's not even going to keep state on the ACL, unless the established key-word is there, but that is usually used for outbound traffic to get back into the network through a router acting as a firewall.
Though "if I initiate connection from outside to 1 of the publics IP's the returning traffic will flow to the initiated interface or will go to the less metric route?" i'm not sure I understand this statement.
Are you trying to state:
Will the returning traffic flow go back through the interface it was recieved on? If that's the question (Answer) -- If that is the only way to get to the original source of the traffic, then yes it will. But if there are two ways to get to the original source, say through interface f0/0 and f0/1, and the traffic was received on int f0/0 to get to the server, then you have a 50/50 shot of it going out the f0/0 interface.