Don't let him hop on your back unless you want him to think of you as a hen he can mount. I'd just stand up whenever he tries to do that and / or push him off you. I don't mind a chicken that wants to hop in my lap, but I don't care to have them on my shoulder or near my face. They sometimes get impulses to peck shiny things like eyes or earrings.
Other behaviors you want to watch out for is at some point as he matures he may "test" you by trying to chase you, herd you, or peck you. Don't ignore those as they'll escalate.
For expressing disapproval, pick literally anything you want just make sure to use consistent body language, voice tone, and cadence. My preference is to stand tall, hands on my hips and elbows out, shake my head and say "no sir!" If he persists I'll then move him out of my personal space gently but firmly with the bottom of my foot. I don't even mind if he takes a peck or two to save his ego as long as he backs off.
One posture to avoid with chickens in general and roosters in particular is leaning forward and staring at them. For one thing, you're putting your eyes in beak-range. For another, you're mimicking the "challenge" posture a rooster takes to start a fight.
You shouldn't have to do anything special when you're going about things like collecting eggs, etc, but do keep an eye on him and watch is body language. If he seems curious or relaxed, it's OK. If he starts getting agitated then have some treats ready in your pocket and try distracting him with that. Or you can simply treat him before you approach the coop and he'll be too busy stuffing his face to worry about what you're doing there.
Another trick to making friends with your rooster as he matures is if you do give treats to your flock on a regular basis, put them out so he gets to them first. He'll usually make his "tidbit" noise to the hens and act like he found this amazing stash for them. You become his buddy that helps him get laid. Otherwise if you hand out treats to the hens first he may interpret your actions as that of a potential rival and you'll have problems later.
Unless it's something dire-looking, I tend to wait until night-time to grab them for health checks / wound care / etc. They don't see well at all in dim light and they get kind of lethargic when the sun is down.
As far as "hand feeding" goes, if you can manage to do that without getting pecked then kudos to you. I have one rooster that eats like a jack-hammer and my alpha rooster is too shy with people to get that close to someone.
This has nothing to do with a young cockerel(Chick) behavior. I've had plenty climb on, hop onto me, & turn into gentlemen, & never identified me as a hen, only as their keeper.Don't let him hop on your back unless you want him to think of you as a hen he can mount.
If he's physically trying to mount a person, then that's a different story. I've raised many cockerels/roosters over the years, & had very few human aggressive ones. It's linked to genetics not personality.