Pulse oximeter - 4 questions :-)

Hello,

Tell me please...
1. is there any point in using pulse ox when living on alt about 80 meters above see level?
2. Is there any temperature above which it make sense to turn the pulse ox on?
3. Is there any option to start pulse ox 'on demand' for example in the morning, after I wake up (not all day or all night)?
4. How does acclimatization work? I know that it is somehow connected with heat and altitude but I can't see any widget connected with acclimatization

Thans for your helop