I know this was a long time ago now but have fixed most of the issues.
1: Plugged in a after market stereo and it worked fine so was probably a dud stereo
2: Tried a multimeter on the lock button micro switch in the fob and found there is no continuity along the switch so have found some new switches on ebay so must be a common fault.
3: The fault where the speedo hit zero and lost power steering was a speedo sensor fault which was fixed at the garage.
yet to have a look at the windows switch lights on the door but noticed that they work more in extreme cold weather so not sure what that is lol.
Just thought I'd update my findings incase this is of any help to anybody in the future