Yes, the unpacking link is the correct method.
Updating a whole site is not a big deal, however, 10-20 minutes and minor manual adjustments should be calculated.
Going from one patch level to another one (like from p16 to p20) basically is:
- dpkg -i checkmk…new.deb
- omd stop mysite
- omd su mysite
- omd update
- omd start
- exit # leave the site user shell
- You might apt-get remove the old Checkmk package when no site is using it any more.
Carefully read the output of omd update, since manual interaction might be needed. For example, some password hash algorithms are soon to be deprecated, affected passwords must be reset before upgrading to 2.2.0.
Anyway: Reading the article on updating and upgrading helps to understand the whole procedure.