Did anyone in San Jose know anything about hockey before they got a team?
Yes.
You have to realize that San Jose / Silicon Valley is a region of transplants - an area that boomed (from the mid-70's onwards) from a small city with agricultural roots into the 10th largest city in the US and one the technology capitals of the world.
Large numbers of people (myself included) moved here for jobs - from New York, Boston, Chicago, Detroit, St Louis, Canada, etc. A significant chunk of STHs I knew from the Cow Palace days grew up watching the Rangers/Isles, Bruins, Hawks, Wings, Habs, Leafs, Flyers, Caps, etc.
And, unlike what people have observed in some other non-traditional markets, most of those fans switched allegiances (or at least became Sharks fans in addition to their old teams). It was not a case of fans only showing up for games against their old teams.
It was an area with a highly educated and affluent population - with a large amount of disposable income and a huge corporate base.
It was the plum location of all the early 90's expansions - which was why the League jumped through hoops when the Gunds threatened to move the North Stars to Oakland.
It also benefited from what I'll call the New York Islanders Syndrome - an area hungry to put it's name/identity on a team to step out of the shadow of it's more well known (and significantly smaller) neighbor up the peninsula - similar to what I witnessed on Long Island in the 70's.
Possibly with the Seals/Golden Seals in Oakland. San Francisco also had a Seals team in the WHL(minor pro) before they were granted an NHL team.
I don't think the Seals (and certainly not the WHL version) had a large impact on the success of the Sharks. Relatively few fans I knew back in the early days had more than vague recollection that the Bay Area had a team in the 70's - a very different time and place. I only knew a handful of fans who had ever gone to Seals games.