Hi,
I have same car and engine and almost same age.
To diagnose the thromostat, if you are stuck in traffic, does it stay at 12 o'clock, and if you start driving say, above 50mph for 10 mins, does it go down to 10 o'clock?
If so, the thromostat needs replacing. I did mine two weeks ago and now it stays on 12 o'clock all the time
Also, check your oil level on these engines, they can burn 1 litre of oil for every ~600 miles (as stated in the manual).
I do not have a high pitched noise in 2nd gear btw.