Bicycle Mechanics - lining up chain ring with rear cassette (HELP)

This multi-speed thing is a bit new to me so...

I am setting a bianchi road bike up with a single ring in front, and a 4 speed freewheel in rear. (w/derailleur)

my question is should the chainline come strait back and center on the freewheel, or do I choose one of the speeds on the freewheel to set as a strait line. I am going to need this info to dish the wheel...correct?

I hope that made some sort of sense...

front ring should line up between cogs 2 & 3

and dishing: just kind of falls out of setting your chainline - you won't really be measuring anything to set dish, but I guess you can measure how much you need to redish

do you know how to measure the chainline?

thanks, thats what I was thinking. I just wanted to make sure.

dish time

You might ask the question-
Which gears will you use the most?
and "favor" the CL slightly in that direction.
Since you're only using 4 cogs, you have quite a margin (relatively speaking) to play with anyway.

how much lateral movement can a chain line handle? i see 10 and up speed cassettes on two chainring drives, is there a max, is it possible to have a 7 speed or more cassette with one on the front?

Of course. Think of the middle ring of a 10-speed triple. It is on the same chainline you'd use with a single, and can get to all of the cogs. Or for an example with the same chain you'll be using, the middle ring of an 8-speed triple.