Now, that picture is useless. The cam gear indeed matches up with neither the nail polish marks or the timing mark.... it's just confusing to people more than anything, I think. Now... a popular method of doing the belt change is to put marks, usually with nail polish, on the belt that overlap to the cam gear and timing belt gear. You then transfer the marks to your new belt, tooth for tooth, so everything matches, and apply the belt... matching the marks on your new belt with the marks left on the cam gear and timing belt gear. These marks do not deal with the TDC marks at all. The TDC marks are the true "in time" indicators... but the nail polish marks are simply there for getting the belt back on easier and keeping things "in time."
As far as checking your work when you're done... you could do with only checking two of the timing marks. If you have a stock flywheel, you could check that too. They'll all be very close but not entirely lined up. Don't let this freak you out. We're talking... the flywheel mark might be off by 1mm or less but the crank and cam TDC marks will be dead on. That's fine. Ideally you should still be at TDC when you get your new belt on... if you're not though, and you can still turn back slightly and line up the timing marks, you're still OK.
When you turn the crank over (which can be done with a socket/ratchet, yes) to check that the belt is turning smoothly, etc - give it atleast 2 turns indeed. Your nail polish marks will not line up anymore... they shouldn't. The timing marks, however, should all still be in sync. After your 2 turns, line up the cam gear mark again and check the crank and flywheel marks... they should line up. Assuming the tensioner stuff is tight and installed correctly, this means you have just changed your timing belt successfully.
EDIT: Yes, you only "need" to undo the passenger side engine mount... but in retrospect, an engine hoist would lend a helping hand to raising the engine and holding it in the necessary positions. Don't let that stop you, though. It's very doable with just one person... just takes time. Have a beer or two mid-way through to keep the nerves tamed.