b) What voltage is normal? Is 13.4 too low?

That is low. A charging L-A battery will be at/near 14.4v.
You'll have some drop between it & the buss, but...

...Under what load do yue see 14.4? How long after starting?

That's 13.4 or .5 in cruise flight, with two nav/coms and strobes on.
Probably turning 2300 RPM, say, ten minutes after launching.

What is the voltage at moderate RPM with no loads,
& with the JPI on so you can see its reading?
With every frigging thing on, including the Jacuzzi and the landing
lights? [We'll skip cycling the gear....]

Dunno. I'll have to record these, next time I fly.

The sealed battery is maybe a year old. Cranks just fine.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"