In the first place, WD-40 is not a penetrating oil. One of the best penetrating oils is PB Blaster, however, while worth the try, this may not solve the problem. Perhaps some of the pro plumbers are familiar with this type of flange bolt, but they don't sound like anything I'm familiar with. If you can't get enough torque to break the bolts either loose or off, then you may be able to drill the head of the bolts. After the toilet is finally off, I sure inspect the condition of the flange before reusing it. The cause of the leak is of course the movement which destroyed the wax ring seal and even if you could have tightened the bolts, that would not have fixed the problem. Once a wax seal is broken, it's game time for that seal. I certainly agree about stainless steel nuts and bolts.