pool node available but has a blue square

Blue square just indicates an absence of a health monitor. You can apply health monitors at the node or pool level. The ones that show green once you click on the member should have a monitor defined at the node level.

the ones that are green and blue have the health monitor "inherit from Pool"

If you navigate to Local Traffic -> Nodes, do the ones that show green once clicking on them in the pool also show green here?

yes

is it better to have the monitor on the pool (which I assume will monitor the pool members under it) or at the node level. If there going to all be monitored on the same service would it make sense to monitor them a the pool level? Or it the pool level monitor on for the pool its self without the members?

Also, would a blue square stop processing traffic for that node?

Thanks!