For T-moulding, you'll need a slot cutting bit. You'll probably also want either a flush cut bit or a template bit, or both.
If the only thing you'll ever do is make bartop cabinets, you can still get by with a laminate trimmer rather than a large router. On the other hand, if you think you'll be doing other types of woodworking a 2.25HP multi-base router isn't a bad investment. I, personally, have the Bosch 1617EVSPK. If I were to buy today, I'd be very tempted to get the DeWalt 618B3 kit with three bases: fixed, plunge, and D-handle.
I'm not saying you won't need to make an ventilation holes, but I'd put the cabinet together and see what happens. If worse comes to worst, you can probably make lots of small holes with your spade bit rather than investing in a larger hole saw. Not that hole saws are expensive, but it sounds like you're trying to keep expenses down...