ah crap! first thing. Go to Kmart & but a mattress protector. They sell single bed ones which are not the PVC backed ones they are a PUL backed one (same as used in MCN) for $20. Maybe even buy 2. Every bed int his house has a cover on the mattress!

As for the mattress now.... I would try hosing the effected area. Place it so the water can drain from foam & then get DH to help wring it out best you can. Maybe try rolling it up with towels/newspaper anything that will help absorb the water & stand on it etc.
try & get as much water out of it as possible. Then yep, cover it & work in Bi carb soda.

Your bed.... Feather doona... sorry no suggestions there, machine wash & then drier maybe? But Aren't those things meant to be cleaned "professionally"?

Further prevention. LOTS OF TOWELS over anything he is sitting laying on & a big bowl/bucket close by!