Where to log meeting hours?

Scrum isn't going to tell you this. Scrum is a lightweight framework for solving problems in complex domains. 



How to log hours isn't a complex problem, its organizational admin. 



My personal answer as a practitioner is that logging hours is an archaic outdated practice that does nothing but annoy people for no reason. The cost of a scrum team is fixed, so where they spend individual hours is irrelevant. 



The best answer you'll get from the scrum perspective is 'A self managing team can figure that out for themselves'. Make the requirements of the process transparent, and help the team inspect and their practice and adapt it to their specific challenges. 

As a part of agile, we do daily scrums and regular functional KT session with product owner?  Where these efforts to be booked?

Nowhere. Nowhere at all. What you're describing is collaboration between Scrum Team members: in your own words it's "part of agile". That's it. You shouldn"t let a book or booking system get in the way.

If these activities are exceptional, and require booking arrangements, find out why.

Thanks for reply

Point taken.

There is often a temptation to over measure.  This may be a good case.  You may be spending a lot of time logging and worrying about a minute detail.

If you have a cup of sugar, you don't need to measure each grain size or count each grain to ensure you have a certain volume of sugar if you're making a pie.