That's correct, the N75 is the one on the slam panel, 2 vacuum hoses and a electric plug, the hoses are actually sightly different sizes, so shouldn't be easy to mix up, unless they get a bit old and flexible, as most will be by now - see pic pinched from
If you can remove the hose which leads down to the turbo, you can actuate the vanes, you'll see vacuum building up, and at a certain pressure, you'll hopefully see the diaphragm rod start to move - hold it a while to make sure it holds vacuum, and them release, if all is well, you'll hear the soft click of them closing again.
As regards to testing the valve, you'll need to disconnect the inlet hose - running to the vacuum reservoir and connect your tester, with the engine started, you should see the vacuum build, with the revs increased, you will notice this sharply return to zero once the valve opens, and build up again - on the outlet you will see the same, but in opposite, little/no vacuum at idle, and when the revs rise, and the valve opens the vacuum will increase.
The vacuum system is quite simple, hose from diaphragm to N75, hose from N75 to vacuum reservoir (under intake manifold, supplied by vacuum pump)
Re: unplugging the MAF, mine didn't throw any codes, and drove as before, albeit with increased fuel consumption.
As for removing the turbo, don't be too rash, it's supposed to be a pig of a job, and often the manifold studs snap - if the vanes are blocked, there are treatments which might help unstick them - some even use oven cleaner, but I'll leave that for you to research....
EDIT - I see Johnny beat me to it!
Also, just noticed you have an auto? any history of work done on the box - oil changes etc? I've seen plenty of auto gearbox issues manifest themselves as other issues.