I wouldn't use toggle bolts. The laminate can still shift over time which can compromise the toilet seal. If yr gonna do that, then you should first tapcon those pieces of laminate to the concrete; i.e., don't let that section 'float'.
As far as the vapor barrier goes, concrete doesn't stop moisture or vapor. Polyethylene does. You need a moisture barrier UNDER yr slab. I'd first excavate all the insulation and dirt from around the pipe, then cut a 3" hole in 9mm or better pe and thread the toilet flange with it. Then 'crete on top of that - for stability and support, not for vapor prevention.
You also want to know whether the rest of yr slab has a vb under it. If yes, then don't put another one on top of the slab. Moisture has to have a place to go - trapping's a nono.
If yr having staining probs, you might consider putting in Subflor or Dricore. They're fairly cheap T&G OSB panels that ride on corrugated plastic channels. The channels protect the floor from moisture and even minor flooding. It's perfect for laminate, since the panels are floating also. However, around yr toilet, you should tapcon the panels into the 'crete and then screw yr flange to the panels. I Subflor'd my basement bathroom and I love it. Really warm.