first car, but.... (i searched)

[Pulse]

First off, hello! im a 15goinon recieving his first car, and i absolutley love my 90' fastback. it has 130k, 5sp, decent interior, great paint (repainted), a nothingtobeproudof sohc, and basic options.

now,

the speedometer (as noted by previous owner) doesn't always function. it always is on speed, when it is measuring it. it may not work when i start it, and it only stopped working while driving once. it is a standard gauge cluster (which i would like to change to the hud, if possible?) i did search, btw, and all i got were people asking the same questions with no answers.

the car only idles at 650, mayby, after its warmed up. it has to be slightly revved to start it most of the time (not alot, i know about revving cold engines). i dont know what the supposed idle is, it is not on the emissions control label (as the manual said to check). it only seems wierd because by mom's hhr (5sp, 4cyl, 2.2) idles at 950.

being under a 96', it is an obd1 system. how useful is the e-mance software for obd1, as in what can you measure/track/read/diagnose?

now, for later on what would be more advantageous, stickin some bells and whistles (and a hairdryer) on/in my sohc or swap for a dohc (or other engine if i find a deal) and go from there? it is a daily driver, so im not goin full on, 400whp insanity, id like to keep my gas money in my wallet.

thanks for the help, glad to be part of the forum.