Definitely a stressful situation, especially for a first-time buyer. I think it’s reasonable to ask for an extension of the contingency period if you need extra time to get these additional inspections. I would also seek the advice of your realtor regarding the items that were not disclosed, especially the water damage.
Let the seller know that you want paperwork for the roof and any other big-ticket items that were done to this house — including plumbing and electrical work. If the guy is a licensed plumber, have him draw up the paperwork describing the work that was done, the quality/type of copper or piping that was used, any warranty information, etc.
Always know that you can walk away, and don’t be afraid to do so if you feel that people are hiding too many things from you. IMO, that’s not a good sign, but it’s not necessarily worth blowing up this deal if everything is really okay.
Maybe ask Parra what your next step should be??? Your realtor really should be helping you more. Make him/her step up to the plate; you need to demand proper representation.