I have only lived on a boat for no more than about six months at a time, but have owned a 37ft schooner for over thirty years. You can soon get used to living on a boat, but space is very limiting. Maintenance costs are high, and the boat will need to be slipped about once a year - where will you live while this is happening? State governments are prone to making expensive (for you) decisions on equipment, inspections, registration, licencing etc, that could really make life difficult.
Living in a marina can be inconvenient, as others have pointed out.
Some places/marinas prohibit living on board - this is particularly common in Qld (the prohibition I mean) although in some places a blind eye is turned. You should check on state, council and marina rules and regulations before committing to it - just because others do it does not mean it is legal.
The cat should adapt readily and easily, but note that having a cat on board (or dog) will make visiting most national parks illegal.
john

