Can anyone recomend which microcontroller I should be using? Is there a PCB already made for this or will I need to build one?
The only recommendation (a good one) you are going to get from this forum will be a '51 derivative.
I am particular to the P89C51Rx2 and P89C66x series for industry standard derivatives.

If your concern is development tool cost and the cost of the product is not imporatant the Cygnal series should be a good choice, they will, however, lock you to a more expensive chip.

For Cygnal go to www.cygnal.com, you will find development boards with tools for $99-$200.

For Philips development boards go to www.phytec.com, again board and tools in the $99-$200 range.

The Phytec tools include a form of ICE which, if you need and want for the industry standard derivatives will codt you $500 - $10000 (my choice, CEIBO $1200)

Note that in both cases the tools are 'demo versions' and only allow you 2-4k of code, which, by the way should be plenty for what you describe as your application. A good non-demo C compiler will cost you
$1500-$2500.

Again, are you going to make one or a thousand units, that is the most important factor in the decision.

Erik