1. Yes, when outside air temp is low, but a thermacter-controlled air cleaner (mid smog years) does very well and costs almost nothing. Downside: if original appearance is important, some surgery to hide where the snorkel enters will be needed, as well as a "stove" partially covering the exhaust manifold.
2. it seems to me that the highest (safe!) temperature keeps the electrical load low since the working cycle will be short. What I can't figure is how to insure maximum contact for conductive transfer between the bulb and the manifold parent casting. It doesn't look safe to just stuff it in a tight, bored hole, the bulb probably shouldn't flex at all. If there's an air gap (bulb doesn't touch the manifold except at the threads) transfer will drop off since there's no convection (only radiation). It could be bonded in place with one of those high-heat transfer epoxies, but how to repair if it fails? Should be easy to test using a scrap block: how hot is the other side of the sample when the bulb is lit for X seconds, etc.
Your choice of location sounds right - the mixture will wash over the heated floor and vaporize before following the vacuum signals to the individual ports.
