Any of the lighter finishes bug me, they tend to appear "dirtier" than their counterparts more often.
There really isn't a need for regular "Above and beyond" maintenance unless you do something crazy like "I shot three cases of paint, threw it into a ravine, and used it as a hammer!"
If there isn't anything wrong and you do basic care, you should be fine.
The OCD freaks of the forum, myself included, tend to be a bit more meticulous. I break my markers down every few weeks, check the internals for wear, give a good cleaning, and light oiling.
The items to look out are the following.
-leaking down the barrel is usually the oring by the tophat with the stem
-reg creep is the reg running dry or being wonky
-farting is usually the operating pressure being off
As for your fittings, if they have some miles on them, just swap them off. CCM fittings are very aesthetic, but some people tend to find them to be a hassle. I haven't had any issues with the CCM fittings, but some people have sworn them off because of headaches.
I do recommend buying a valve tool, it is something that any sheridan based owner should own.