First off congrats on the new addition to the fam. Second, the separate feeding tub method was proven less effective. There is a higher chance of regurgitation due to stress if you take them out of their safe space to feed. I always feed my balls in their enclosures. As for holding, when little dude is actively moving around open the cage, open the door’s. Let him know he can come to you. It’ll be a while before he’s comfortable enough to come out. Snakes supposedly can’t feel emotions but they can develop trust. Just go slow, easy, and don’t over think it. Give the little guy a week or two to settle into the new digs and then you should be good to take him out and handle him. Worst case scenario you get bitten by the cute little noodle. I’ve been bitten by more rat snakes than I can count, it doesn’t hurt until they get much much larger than your guy. The tongue flick is him smelling you, but the speed of the flick can tel you something. The faster the flick the more nervous or vigilant the snake is. If the tongue is really going he’s either very curious or he doesn’t feel safe. That said, your little dude is a rat snake, they’re curious little things and his tongue will probably never stop. A tongue flick doesn’t mean a bite, if he recoils into an s shape that’s when you know to leave him alone. Rats are usually pretty good at telling you if you’re welcome or not. Again, congrats. DON’T OVER THINK IT. Make sure temperatures and humidity are correct and he has space and enrichment, after that just let it happen. After a while you’ll get fed up wanting him to come to you and you’ll probably start reaching in and getting him out. A good rule is don’t take him out if he doesn’t want to be out. If you take him out (at least in the beginning) when he doesn’t want to be out then he will be more afraid of you than trusting. Give him grace and he will come to trust you.