90psi is the max rated for the particular tire, but does not really apply to aged tires!!!

Basically, inflating to max means that you can ride longer before having to re-visit the tire pressure, a nod to our pre-retirement lives when the time to do such things might be found wanting.
Optimal pressure (somewhere below 90psi) will depend entirely on the load on the tire and on whether one may encounter road defects or stones with perhaps sharp, square edges (which could pinch the tube and possibly dent the rim upon impact)

The patch glue must be COMPLETELY dry before the patch is applied, otherwise the patch is ruined and the intended "vulcanization" process will not work as intended.

Could be an issue with either a bent axle or something going on with the dropout which is preventing the axle ends from settling consistently into the fork dropout slots.
You need to make yourself aware of how the installation steps might affect this.
Possibly the dropouts are bent in this way or that, or that the wheel is not symmetrically "dished" with respect to the rim being perfectly centered between the axle locknuts that bear against the fork dropouts. Try flipping the wheel around first(?).

Adjusting cantilever brakes is an acquired skill, the product of endless tinkering and perfectionism leading to quiet, responsive braking.