I shared your same concerns about oiler vs brush, and I ended up by using the glass tool that comes with the SL kit.
I think I used too much varnish with respect to the powder. I had to apply two coats in order to make the coat homogeneous, and in the end the applied coat looked quite thick (quite high, I mean, not quite dense).
It took ages to dry out.
After a few days I became impatient and rejoined the upper dial layer with the inferior layer (where I had applied the lume) without waiting for a complete drying out (which I still wonder wheter a week would have been enough).
Result: the lume was all but dried out, it penetrated into the clefts of the sandwich dial bulging towards the outside (upper side) and giving the whole thing quite a silly look.
I had to separate the two layers again, cleaning them both (a pain in the ass), and starting all again from scratch.
About half SL kit wasted, too.