Questions about Polar A370

Bracelet size S or M/L could you give a little more precise info on this. Circumference for S = up to XXcm?

does this heart rate monitor work with the heart rate monitor? which heart rate monitor is compatible? thank you very much.

How much does size M/L ind cm measure?

When I wear the watch for too long, my skin gets red and itchy. I have disinfected the strap, unfortunately without success. Is there anything I can do about it?

I have a Polar V800 and would like to buy an activity tracker (like the A370) for the "non-sport days", as the V800 is rather clunky for in-between. How does it work with the Polar Flow app? Are the "display my activities" shown together, or are the watches listed separately from each other ? Does that work at all?

Where can I get the Polar A370 ( L ) with 226 mm . (M/L) is only up to 200mm strap length and in black.

M/L which wrist size corresponds? Can the silent alarm be set?

I have had the watch for just over 2 weeks now and have completed 8 workouts in that time. During 5 training sessions, the tracker went out of training mode and displayed an error. All the progress of the training was deleted, which is quite unpleasant, as this is actually the main function. Will this error be fixed? Is it already known or is my case an exception? Would it be possible to get a replacement?