The offset would be 0 vs stock 38, i.e. your wheels will be out 1.5". I'd don't go with it. I'd look for the same wheels with back spacing no less than 5.5 (http://www.rsracing.com/tech-wheel.html).
If I correctly understand the term, the front wheels are hub centric, the hub diameter is 100 mm (it is possible to install wheels designed for bigger diameter, but not smaller). And there's nothing wrong to install hub centric wheels on the rear (I believe they should be different by the hub cup size, but check if the hub cups are supplied at all).