It is kind of oral sex; that may lead to intercourse sex. Per Islam teachings, this kind of sex is not allowed unless being practiced between husband and wife who are licitly married.
Get a girlfriend
Stealing someone's girlfriend is a big NO-NO. The thing you need to do is find your own girl without a boyfriend.
get your boyfriend to hep you
You should be confronting your ex and telling him you do not like his girlfriend asking your children about your new boyfriend and if it keeps up he will only be able to see his children at your home or without his ex girlfriend.
The one that likes you without a girlfriend.
due to harmonal changes
Nothing. He has a girlfriend. He did not say he wanted to go out with you, he said he likes you. You can like someone without wanting to go with them.
She probably had a boyfriend in mind and did not know how to break up with you without hurting your feelings.
you can call each other boyfriend and girlfriend without going on a date, even if you have only both established clearly that you each have feelings for each other.
If you did that, she would be uncomfortable. She might not want to talk to you if you just call her beautiful without even getting to know her a bit more. What you should do is get to know her first or even be girlfriend and boyfriend with her.
they are together without a label because one of them is scared of commitment
Personally, I think he is rather immature, and you are best off without him!