It's quite thick and I have used it in your situation with no issues. You should feel resistance when pushing the toilet down to the floor. If, when placing the toilet, you don't have to push down on the toilet to make it reach the floor, just lift the toilet and place another regular wax ring on top of the thick wax and replace the toilet. Just remember, wax is not "springy" so will not return its shape once pressed.
Yes it will BUT when you install the toilet you must feel the wax ring compress when sitting down on the toilet to make a positive seal, if it does not you need to buy the inexpensive single wax ring without the flange and STACK it on top of this and reinstall the toilet
No. They are steel with a gold colored coating.
I installed it by putting the ring on the flange, install the bolts and the carefully putting the toilet on the wax ring.
longer than you will ever need, you will have to install the toilet and then hacksaw off the excess length
It should do fine
Yes,it can be used with any toilet.
in my experience I would use a waxless type .