Urushi Adventures

I just got some urushi from a woodwind instrument maker.
That urushi was lying around his stuff for many years unused, so he let me take some.
I filled few metal tubes and tried to copy the labels of the originals and also got few smaller tubes with stuff he said is urushi sabstitude but since i know cashew urushi already i know the tube looks diffrent.
I started working with what i think is roiro urushi which is very black and thick, trying to make some loose flute joint snug again,
its preety dry after 2 days in a humid box but got some stuff that looks like dust particles in it and also few wrinkles although i tried to paint in the thinnest layer i could.
This lacquer is beautiful! i also think im lucky to be not allergic to it since i touched it few times, washed my hands and nothing happen.

I got so many questions but no one to ask them and also couldnt find the answer anywhere on the net.
what is written on the labels?(-see pictures)

how can i filter the urushi other then the traditional paper method?

should i filter it at all?

should i always use shuai urushi (that brown translucent one) as a primer before the others?

How can i polish it/sand it/etc?

how long does it take to dry before you can sand it/ put the joint together?

and also specifically how can you know if you got a fit when you work on a flute joint? because the flute swells moisture and the joint is tighter then it is normally.

Any info would be appreciated.

Thanks!!