Welcome to the Werkz! You should have posted this in question in a vehicle specific section of the forum.
I'll do my best to answer your question though...
I believe your wheel hub size is 72.56mm vs the 74.1mm bore size of the wheels you are looking at. First thing you will need to do is buy a set of hubcentric rings (you can buy them pretty much anywhere) and then to change the offset you will need to buy 20mm wheel spacers.
You are correct about the hubcentric rings. They can be purchased for ~20 dollars on ebay.
However, as far as the offset, you are wrong. The lower the offset, the more a wheel sticks out. If he was to fit 20mm spacers, he;d push them out so far, he'd have to remove the fenders all together.
OP, yes, you can fit them, but be prepared to roll the fenders and run something like a 205 width tire; otherwise it's gonna rub like hell.
edit: I guess you could take them in to a machine shop and have them slice off 15 or 20mm off the backspacing off the new wheels to make them the 'correct' offset for your car.