best is to read through as many posts as you want, look at youtube videos especially S.A.J 's window cleaning, and then decide if you would like to go DIY or fully installed, the later being more expensive. i would advise trying to get a days work with a wfp guy to get shown the ropes because it can be frustrating, as for trolly or van mount, i think im with most people when i say van mount is preferable, the results are the same but you will get tired of filling up from barrels, if your water is hard ie above 100tds (a meter will tell you this) you will need an R O system, reasearch these on here to decide what you need