Plug the cold-light head's heater in about 1/2 hour before you start a printing session. Expect some exposure inconsistency even with the head warmed up - it is the nature of the beast. I used to leave the enlarger on except for the times when I was loading the easel or developing the paper. I finally got rid of the cold light head and life improved - YMMV and all that.
A compensating timer (properly an "integrator") can help a great deal with print consistency when using a cold light head. They haven't been made for some years, though RH designs may still have an integrating variation of their f-Stop timer.
If you plan to do split grade printing make sure the cold-light head has a fluorescent tube suitable for variable contrast paper. I had an early head that would print at grade 4 1/2 with no filtration, with a #00 filter I could get the contrast down to grade ~2 1/2, maybe.
As to the size of the garbage can - the bigger the better. Kodak projection print scales, split grade printing, f-Stop timing and metering work more to increase the quality of what you don't throw away. The waste basket only fills more slowly if you keep your standards at the same level as you increase the quality of your tools.