Hi Graham,
Re:"How do I check to see the battery's being charged, and also, check it's not being over-cooked!?"
Having just fitted coil ignition to my Comet, I noticed that the old battery was not able to supply power to the lights and the ign system for starting. I fitted high brightness, low wattage, LED sidelights and a Sprint 12AH Gel battery encased in 3 sides and lid of an old exide rubber battery. It was all assembled and stuck together with silicone sealant.
To check voltage and charging I have fitted a Battery Status Monitor from AO Services.
http://www.aoservices.co.uk/data/bsm.htm
I have fitted it (a 10mm led) between the headlight and bracket behind my tax disc, leaving it visible to rider but totally unobtrusive as its ribbon lead is taped to the headlight shell and the 5/8" electronics box and connections are inside the headlight.
It runs through its colour range once connected, then settles to indicate voltage. It is sensitive enough to then change colour as the ignition is turned on. I am that impressed that I have another to fit to my Knight, possibly repalcing the redeye in the ammeter. Only two wires to connect, red and black and it doesn't blow up if you get them wrong!
Not standard, but discreet enough to get away with and it saves worrying about flat battery or overcharging and saves having to check things with a multimeter.
Cheers, Ian (See you at the SW Autumn Meet?)