Adhesives for the teflon washer - I float my washer, i.e. no glue, I just make sure the teflon washer is tight on the axle so that it stays where I put it. Other may weigh in on other methods.
Trimming back waterslide - if you are just putting on the flat surface - cut to fit, if you are running over the edges you will need to make scores in the waterslide at the four corners - and it will lay pretty good. Sometimes I press the waterslide in as the first clear coat get tacky. Press it in real nice then sand with some real fine sandpaper (1000 or finer). Then your second coat of clear will seal the corners/edges.
It's pretty simple once you do a couple. I always print an extra waterslide or two in case one rips - the more you do the less mistakes you'll make. The good thing about waterslides is if you are not happy with the way it's going or if you tear - just pull it off - throw away - and try again