I would say if you are wanting to see cape trib I would say you should stay in Port as its nice and family orantated(sp?) plus that way you could drive down to cairns if you wanted to and drive up to cape trib but most tours offer free transport and everything that leaves out of cairns will also tour out off Port... I think that Port is more like a hoilday place iykwim but that could be because I live in cairns so dont see it as a hoilday just see it as the place I live, But we love to go up to port and visit the market up there very worth a look... I have know I idea where to stay up there sorry but most place are pretty good with kids so dont think you will too much of a problem..

As for swimming I would say stick to the pool ( there was a croc swimming in the nets on the weekend ) I dont ever swim in the beach but I do know people who do though.... ( but I came from Darwin where you just cant ever swim dew to crocs lol)