Just a couple of notes.
First the Jetstream. What do you expect from an aircraft that was designed by Scotish Aviation. The true Scots are known for being more than just a little on the cheap side.
Second, altimiter differences. That is true of all aircraft that have separate pitot/static systems for each side of the panel. Until you get into RVSM aircraft. The only time I have had altimiters read the same is when something is wrong. So if you see both altimiters read the same, 'Be afraid, be very afraid'