[CentOS] a few simple questions about upgrading an "official" centos 7 release

  again, some fairly trivial(?) questions about working with centos
7.4, given my time immersed in fedora so i want to make sure i'm not
carrying over any bad habits.

  first, is there anything untoward in updating an installed version
of centos 7.4 with a simple "yum update"? i'm well aware of keeping in
mind the goal of stability with centos, so am unsure what the
philosophy is of pulling in new updates as cavalierly as i do with
fedora. currently, "yum list updates" shows me 206 possible updates;
should i have any concern about updating packages coming from the
standard centos repos?

  next, are there any issues replacing yum wihth dnf? i found this
piece:

https://www.vultr.com/docs/use-dnf-to-manage-software-packages-on-centos-7

which suggests it shouldn't be a problem. thoughts?

  finally, any concerns i should have about upgrading the kernel from
3.10 to 4.14 or 4.15, as explained in a number of places like this:

https://www.tecmint.com/install-upgrade-kernel-version-in-centos-7/

  i simply prefer to run a current kernel but i can resist the
temptation if upgrading that on a centos 7.4 system would introduce
more problems than are worth it.

  thoughts?

rday