The floor gasket is not included , however the bolt caps are included.
The 3461.001 is a universal bowl it will work with a 1.6gpf and a 1.28gpf flush valve and the 3461.128 will only work with a 1.28gpf flush valve.
A universal bowl is one that can be used with several different tanks and an elongated bowl is just the size of the bowl.
All floor mounted toilets have a weight limit of 1,000lbs
American Standard defines a universal bowl as one that will operate in the range of 1.1 to 1.6 gpf. The actual flush volume is controlled by the flush valve that is installed meaning that the bowl will operate at 1.28 gpf if a 1.28 gpf flush valve is installed on it.