JP XI – tunning stability and trem arm ?s

JP XI guitar:

1) My guitar stays in tune but i find that it doesn’t take much to bring it out tune. It stays in tune more then a Gibson or a Fender but nowhere near what a floyd rose will do. Is this fairly normal? Side note that maybe relevant: I recently made some minor tweaks to guitar: string change from 10s to hybrid 10s top/9 bottoms and i switched tuning from 1/2 step down to E regular. all at the same time I adjusted the string tension so compensate the floating bridge staying level. Now the tuning thing could it be that the neck shifted or bowed and I need to adjust? I know how to adjust bridge and intonation but clueless on adjusting neck. Could it be the neck position shifted?

2) The trem arm swivels around way too loose for my like. I’m referring its ability to spin around. Is there a way to tighten it up some? I removed the plate and didnt see a screw or bolt to adjust on the bottom side.

Thank you!