Quite agree!! as picaxe as a very limited no. of lines available on the chips.But for simple programming (no programmer required) and resource available a good start as the op. seems to avoiding microchips even though it the sensible option and the beneficial one (in either direction).IMHO Swordfish BASIC is far superior the the PICAxe, an initial cost of a PIC 18F programmer and you're in business.
Choose the size and motors / wheels, then we can figure out transistors.The robot is spose to be really small and simple. I don't really know wahat type of transistor i need or if ill need resistors and diodes, I'm not electricall enginer lol