You should be able to get a Jaiban or Hake brush from most decent artist shops. However, they are not essential as you can use a coating rod (a glass themometer for example). I would suggest diluting the SE1 with equal quantities of distilled water as you use it.
I use a plastic knife to gouge out small lumps from the original bottle to save reheating the stuff - 20-30ml is usually enough to last me a coating session. You only need a thin coat to get a decent image.