1. Should I provide a separate breaker for the combi unit? (The reason that I haven't just DONE IT rather than composing and posting this long question is that the panel is maxxed out - all breaker positions taken - and is so old that I'm not sure I can get a half-width breaker to substitute for one of the full width ones. The brand is Federal, from the 60's. Also, while the wiring run is just the 10 feet noted, it goes around several corners and thru at least one box (the one with the light over the sink) before it gets to the location where the switches for the combi unit will be.)
2. Or, should I just go the easy way and replace the existing breaker with a 20?
3. Last question. I want to put a wind-up time switch on the wire feeding the 1500 watt heater. Will an Intermatic FD/FF series time switch (rated for 20 A) last a long time, or will the heavy load eat the contacts?