The thought of Damian getting lipstick smears all over his cheeks/forehead in your fem Dick hc is the cutest thing ever. I can imagine Damian doesn't always remember to wipe it off which leads to embarrassing situations for him. Jon would either think it's nice Damian lets someone mom him or totally poke fun at Damian of having a soft side for someone like that. Also lets not kid ourselves, Jon would totally get a puppy crush on Fem!Dick (sorry Jon. Damian would not approve of even you).
Ahah oh my god, yes!! He goes out on patrol like that and Jason or Babs just whistle and say something like “aren’t you a little too young to play Romeo?” and Damian becomes redder than the lipstick smears. Jon tries not to laugh to Damian’s face (because he’s a well mannered boy and his mom taught him better than that, of course) when Robin shows up at his window all haughty and mighty and with a clear pink trace of a kiss on his forehead. Damian’s exasperated. A reputation of a lifetime destroyed like that.
And yes, Jon would totally have a crush on Fem!Dick. Which is unsafe, to say the least. The first time he mentions to Damian that his big sister is cute, he goes home to retrieve his katana and lace it with kryptonite. “Say that to my face again, you treacherous, lascivious alien scum”. But then Damian enlists him in his quest to keep away every man he does not deem worthy of his sister’s time (aka all the men) and they kinda bond over that.