Red are for errors. It is important that those are corrected.
Yellow are suggestions. Usually nothing depends on them, but should be tended to.
Blue are hints for possibility for new connections. Usually specially created for some project.
Order of suggestion depends on the list you are watching. For prepared suggestions Primary order is by privacy, so opened profiles are at the beginning. following orders depend on the error type. Some are by info column, some by name, some by dates and some by creation time. Depends on what I decided to be useful. It is easy to correct it, Just ask.