nm36 wrote: Initial drops:
- Is having initial drops with the lever up a strict requirement? I don't get any, irrespective of how long I wait for

Not really. But I find it helps in judging whether the grind is right and it you have let it pre-infuse enough.
If you aren't using a bottomless portafilter, you might not see them anyway.

I do recommend a bottomless portafilter though. It helps a lot in detecting channeling.

You've got great advice here. My vote is on grouphead temp. Best to monitor it with temp strips or a digital thermometer. Start your pull around 84-85°C.

I agree with this. The water stored in the grouphead will be used for the next shot. It will be pushed out by hotter water entering the grouphead from the boiler. Grouphead temperature is what needs to be monitored. I commonly measure temperatures in the mid-90's. The temperature you choose to pull your shot at will be determined by roast level (darker = cooler) and personal taste.

- Is having initial drops with the lever up a strict requirement?

I don't think so. I will usually only get drops if I gently press the lever down for a more forceful pre-infusion. I can see the bottomless portafilter start to show drops. Then, I either transition into a more forceful pull for extraction, or gently raise the lever before proceeding to pull for the extraction. This replenishes the amount of water in the grouphead for a larger volume of espresso.

The dial on the Eureka has a very small diameter, so it takes little movement to change by multiple degrees. It makes dialing in a challenge.