As I scan the bands I find a lot of stations (esp SSB) that are operating on frequencies that end in .000 I'm assuming these are folks who know each other and have a regular schedule? After all it is easier to say "we'll meet on 14.205" Or are we prone to picking frequencies with zeros at the end? I purposely am trying to pick frequencies for my own CQ calls that are not on the zeros. Call me a rebel. What about you? .000 or something random?
Find an "open" frequency. Ask if the frequency is in use. Go for it and don't worry about that nonsense.
Yes, because it makes it easier for everyone to get on the same frequency. Listen in on some qsos and you'll see this is something a lot of hams struggle with.
I like to shoot for 14.033427774665 just to keep 'em guessing It's 100% as legal as 14.030000000000000000000000000000000 This is a "straw man argument" that comes up at least a dozen times a year. It's just silly to even ask, IMO Dave W7UUU