First, take pictures of your entire system including close-ups of serial numbers. This is for theft.
That insurance does include contents is true, but only as a percentage of the total replacement policy on your house. If you live in an area where homes are very expensive then you will have over $100,000.00 on contents. If you live in an area where your house is worth, and is insured for about $120,000.00 then you might not have as much as $30,000.00 contents coverage.
The best thing to do is try to figure out what your belongings would cost to replace, add 25% and then call your agent.
On the part about flooding, be a bit careful here. Some policies might not cover that at all. Note there are differances between water damage. Surface water, water coming back through your sewar, rain damage due to an unmaintained roof, and water coming from a busted pipe.