Hot melt glue works fine to hold the wires and Trinket in place, but can be disappointingly nondurable. E6000 craft adhesive (one of our favorites) dries clear and flexible with a very strong bond, but the fumes are a bit noxious and it takes 24 hours to set completely. Choose wisely.
Using the code as provided, the battery should run for about two hours. Different colors and patterns will have a different current draw and run time; this is nearly impossible to predict, sometimes the best way is just to plug it in with a freshly topped-off battery and see how long it runs.