Check your brake lines to because it sounds like when your pedal fades to the floor it must be leaking fluid somewhere. Also check your vacuum line because it sounds like there is a leaking one. Replace any vacuum lines that are cracked to. Hope that helps. Also bleed your brakes.
A full floater has the axle mounted to the brake drum or rotor and you can take the axle out with the wheel off because the axle rides on the diff and drum/rotor hence the name full floater. Where as a semi floater is just like normal.
Here is a full floater.
Here is a semi floater.
Hope you...