Here is an example of a touch sensor:

http://www.picbasic.co.uk/forum/showthread.php?t=2671

And here is the smoothest dimming, using mibam

http://www.picbasic.co.uk/forum/showthread.php?t=10564

PWM hardware can also be used for dimming, as well as interrupts. But I think mibam is better.

You could use a chip as small as the PIC12F683 for this. Start out by just trying to dim a single LED, then later worry about how to drive your larger LED lamp.