If compressor idler pulley is not turning,the belt would squeal so loud,belt would be hot and shredded in seconds...maybe a minute.
It would probably kill the engine at idle.
That pulley is not seized.
Clutch is a different story.
Speedometer signal goes through abs/tracs module. You have a bad abs sensor(s),their wiring or bad abs/tracs module...VOL-FCR or dealership is needed to read the codes. TRACS is always ON by default. You can turn it off by pressing the switch and TRACS OFF will illuminate on the cluster. Usually...w...
850 OBDII app will work but with specific obdII adapter. I never used it but here on MVS are plenty members that knows how to use it. I'm affraid that your abs module might be replaced somewhere in the past since it always turn on both abs & tracs light. As far as i understand...you have just Ab...
Boost gauge was only fitted to 850 T5 & 850R(high pressure turbo). Low pressure turbo cars didn't had boost gauge. Trip computer for VDO cluster should be the same for all VDO clusters. Yazaki & Vdo clusters for 850 are not interchangeable...so trip computer could not be interchangeable too.