High idle, ABS/ Battery dummy light

Thought I'd post my issue and see if anyone else has experienced the same deal-e-oh before trying to pull codes / seeking professional help:

Before I begin let me first apologize for probably coming off as a total idiot, I literally know nothing about electrics or electronics, especially in vehicles.

For the last six-odd months - beginning in the cold fall mornings - whenever I started up my R after it's sat for a few hours, the ABS light and battery dummy light would stay on until I blipped the throttle, about 10 seconds after start-up. The interior fan motor would also spin more slowly and the dash lights would be dim until I revved the motor a little, then everything would brighten / speed up and the dummy lights would turn off. I figured the battery/ alternator juice might be a little weak and the ecu wouldn't register it until I boosted the signal with a little rev (told you I'd come out of this story sounding like and idiot). That always worked, so it didn't bother me too much. Fast-forward 6 months and now instead of the lights turning off immediately, they also just brighten when I blip the throttle. I actually have to drive a couple of blocks before they shut off, and a few times now both lights have actually come back on while driving, doing so mostly when I'm decelerating. It's starting to stress me out.

Now this may or may not be related, but I've always had a problem with my idle. When the engine's cold, it high-idles as I suspect it should, around 1500 rpm. I'll drive for a few kms, come to a stop light etc and the idle will be around 1100 rpm (not bad but not great). The problem is after the engine really warms up (say another few kms of city driving), the idle crawls up to 1300, even as high as 1500 rpm recently! To potentially tie the two problems together, the last time this 1500 rpm idle happened, the ABS AND BATTERY LIGHT CAME BACK ON!! And by the way, my idle screw is turned all the way, otherwise I'm sure the idle would be even higher.

I've tried putting the engine under load (holding the brake while 50% releasing the clutch) to see if I can "force" the idle down. I sometimes can get it down to around 1200 rpm, but that's the best I've seen it after everything's hot. I know, THAT'S BAD!

Can anyone shed some light on my issue(s)? Grounding? TPS? Engine-idle goblin? Any feedback is appreciated. Cheers.

Ty