Around 30 psi f&r is fine, try a couple of pounds either side and see what you like, in my experience under about 25psi isn't stable, over about 35 doesn't grip and a set of brand new Alpha 10's have given their best in about 10-12 heat cycles anyway.
As far as I can see that's a better arguement for tyre warmers than not having to do a few warm up laps.

As regards accuracy RiDE tested loads years ago, Halfords cheapo ones where as good as any. Just use the same one all the time and find what works for you.

Rain? Maybe, I got lucky at Cadwell yesterday, they'd been forecasting heavy rain for Monday which slowly thought the week changed to rain, then showers, then overcast, then sunny. Sunny was a bit optimistic but we got a warm and dry day.
A few loons went out on wets first session as it had been very misty/drizzly earlier and the ground was a tad damp but they just knackered a set of tyres in 15 mins
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