embarrasingly simple vacuum line questions

[dwest]

I searched but maybe this is too basic.
I am planning to systematically replace my vacuum lines, connectors and fittings. I have no problems now and hope to avoid them.
Since the car (89 300CE) constantly holds a vacuum, when I break into the system to replace a line, the vacuum is lost. Will it re-establish the vacuum when I re-start the car after the replacement? Do you "pinch off" vacuum lines like a fuel or coolant line to isolate the spot you are working on?
Will I need the vacuum testing tool? Which one?
I can't find a schematic of the vacuum system comparable to a wiring diagram. Do I have to buy the CD?
thanks