Depends what you have seen I guess, I have in the past gotten 1960s/1970s race cars, specials and Manx type beach buggys, often left outside for many years to find stuffed gelcoat and swelling, crumbling or powdering.
Not saying any plane looked after will end up the same, just explaining where the mindset comes from for me in regards to old fiberglass.
Absolutely not, there is nothing that can't mostly be replicated on a flat bench at home using stock aluminium sizes, including the wings, some minor steel parts from any local light engineering shop, and about the hardest bit would be getting a new canopy blown.