More context would probably be helpful, but "plant a smooch [on]" means "give a kiss to." "Have a smooch" means . . . well, I don't know what it means, since I've never heard it, but it could possibly mean "engage in kissing."
There's another one "to smooch".
All are colloquial because they are slang for kissing, usually between people who are attracted to each other. 'Planting a smooch' is giving one kiss to another person,' having a smooch' means having a mutual kissing session as does 'smooch'.
"I don't know what happened in the film - we were too busy smooching in the back row".
I would say that ' have a something' is more colloquial. than the straight verb: He's having a shower is more colloquial and natural than He's showering probably because the "have+ noun" constructions tend to have a more pleasing spoken rhythm.