If you're on a tight budget the better quality security cameras can put out a pretty image these days, you can get remote pal/tilt/zoom controllers etc. They'd be adequate so long as you're not moving the camera while its on air.
Planty of vision mixers around, still hard to beat the venerable Panny MX50.
If you get interested in some the more modern digital mixers check out the latency, can be a real pain when the thing takes a few seconds to switch.
Bob.