You will get a good idea about fuel pressure by the mot emissions.
No you do not need a new pressure reg, just because someone has adjusted it, so long as the pressure is correct, the side where the adjuster is is the vacuum side, so if leaking fuel would be pissing out, there may be a minute vac leak but so small not worth worrying about.
Start with your basics, ignition timing, co at idle, is the idle speed adjustable, if lumpy only around idle look for air leaks first, especially on the pcv system, the actual pcv valve itself can jam.
As for the light glowing, if it's charging ok don't worry, just has tiny leak in a diode(one way electrical valve), there were bad batches of diodes years ago, mostly of US origin, but any earth that is sees on the wire between the alternator and the charge warning light will cause it to glow, if a resistor was put in line it would stop this if worried.
tabetha