If water gets into the fuel/h2o canister filter can it be removed by dumping it out and reusing or do you replace it. We recently had flooding here and I am worried water might have work its way into the fuel tank through the vent.

Whilst removing known water from the tanks, you can indeed run and dump, run and dump, repeat...

Once you've got most of it out, you should then put a new separator on. The cellulose in the media gets water in it and it won't dump out.

you can also install a racor filter on the same filter head with a metal bowl & a drain plug in the bottom. A little pricey but it is a great filter.