Alot of milton stuff is made in USA, so you cant really go wrong. "my" filters and regulators are all speedaire from grainger, made in mexico(didnt know it until I recieved them) but they are still really nice. If your using copper lines, you only need 1 filter. With black pipe or galvanized, you need one right before a regulator, directly before each hose. Copper is the material of choie because its so easy to work with. Install the filter as far downline as possible, but before your first drop. Also, use a filter with the same size line your running.
As for filter brands, these Speedaire ones are pretty nice, no problems so far. Milton stuff is made mostly in USA, so you cant really go wrong. Norgren makes some really good stuff, but alot of problems have been reported with thier "automatic filter drains"... basically, its this spring loadedtype thing that remains open until there is X psi in the system, and it is forced closed, but dirt gets in the seal and prevents it from closing all the way and so it leaks air. Get a manual filter drain.
Also, If you do get a polycarbonate filter bowl, make sure it has a good metal gaurd around it. The speedaire stuff we have cost a bit more, but its made of cast aluminum. The compressor oils eat away polycarbonate, and they will eventually "rupture" and its pretty violent when it happens (I know from experience)
A motor starter is a magnetic motor starter. I wasnt too sure what it does, so I did a bit of searching and found out...
"The primary purpose of a magnetic motor starter is to provide thermal overload protection"
http://www.usace.army.mil/usace-docs/armytm/tm5-683/c-5.pdf#search='magnetic%20motor%20starter'
The guy to ask its "tomwelds" as he is an electrician.
Jim