Some general lutherie questions

I had two plastic tuners fall off of a poorly built cheap ukulele I got to practice working on. I wound up putting new tutors on, they work fine but they are loose because the screws stripped on the way in. I'm wondering if there is a glue that I could use just to shore up the tuner connection to the headstock. Gorilla glue?

Also, on a fretless ukulele, what effect does bridge placement have on the tone of the instrument? Like if I move the bridge towards the nut will that essentially "tune it up"? Would this have any impact on sustain?

Finally, with the first ukulele I have been building, I have noticed that the lower pitched strings have much better 16. Is this normal? Any tips for improving this in the higher pitched strings?

I am loving getting into building instruments. Definitely an addiction.

Tuners: Do you mean the screws stripped out the wood on the headstock? You can either drill out the holes, glue in a dowel, then drill new screw holes. Or, find a bigger screw that still fits the tuner hole. Or try adding glue into the hole then put the screw in. I wouldn't glue the tuner directly because you might get glue in the machine.

Bridge placement: makes no difference to tuning. You can tune any length string to any pitch (until it breaks). With frets, the bridge position is set by the scale length....twice the distance from the nut to the 12th fret (plus a little compensation). On a fretless it doesn't really matter. The bridge also has to work with the bracing and bridge patch. Moving the bridge without changing the bracing could kill the tone because the braces won't distribute the vibrations over the top.

Much better 16??