Gas or diesel?
If gas the 454 engine is common to blow exhaust manifold gaskets. If not that a general exhaust leak.
Like above said take a flashlight and ice pick to inspect the floor around an area you suspect a water leak.
The emergency brake is likely just a rust issue of the cable. Inspect from below while someone applies the brake.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles