Raft might be usefull to avoid elephants foot which might cause it not to fit. It should be tight and hard to get on the first time. You can use the bigger allen key to "Drill" out the hole to get perfect fit. After that it should have a snug fit and not come of by itself. I can get mine off without much force. Hole diameter is 3.2mm

Creality

Ender 3

Yes

No

10% is fine