A Couple Of Questions For The Xperts

[Gabaunion]

Hi, I am new {used}Avensis owner with a few questions.

D4D diesel 54 plate Saloon

Timing belt : Is it a DIY job? I have done head gaskets on old Merc diesels etc.

Thermostat : This thing takes forever to heat up, once its there it seems to hold the temperature is this normal? I have had old diesel Nissans that heated up as quick as gasoline. I searched the forum and found a few similar questions, but no clear answer. How long to get to the half way point, and should it stay exactly there? Mine takes about 20m and wavers slightly.

Fuel guage : How accurate are the fuel computer displays on these cars?

Does anyone know how the trip computer works, because I am pretty sure its not measuring the actual fuel being used, but rather displaying from a programed graph of engine speed / pedal position, etc.

Does the mpg clock always go blank when you take your foot off the gas? Or could the pedal sender be in the wrong position?

Bearing noise : Or what? From the front wheels, worse when cornering, no sign of alignment issues but it doesn't feel quite right in a turn also. The noise is a light continuous white noise, with an increase at wheel rotation frequency.