Tacho/rpm needle jumps 1500rpm & boost gauge needle at high, key at on

What engine/year car?

The needle is not set up properly, so one would assume its been removed at some stage, maybe to fit some aftermarket dial faces.  Remove the needle, turn the key to 'ON', put the needle back on at the 0 mark.
 
For the speed sensor issue, its tougher to diagnose, but you would want to check that the ECU is getting any kind of 'SPD' signal at all.  I've got the wiring pinouts for that year somewhere, so i'll look at it later.

Is that instrument cluster the original one that was in the car?  There are known 'issues' with the waferwire board behind the cluster being different from model to model.  If someone has tried to change it and not used the original board, all kinds of funky things can happen lol.
 
The tachometer needle always will 'twitch' when power is applied, as its then looking for a signal from the coil to tell it how many revolutions the engine is doing.  its nothing unusual :)
 
IIRC, there is a single-wire plug at the diagnostic port that can be used as a coil signal, to read engine RPM.  You could try using that and take readings from there.