Seems like San Jose effectively selling Vanicek for cash.
I doubt there would be a market for him without retention. Florida has the cap space to add his full cap hit. San Jose doesn't have to pay his remaining salary.
I don't know anything about Giles but my hockeyDB scouting tells me he is a warm body. Probably a good solid pro. 6'5", you can't teach size. But he is an AHL player, which would make him fit in perfectly on the Sharks NHL roster.
Even if Vanicek is not an upgraded on Driedger, it doesn't hurt to add more goalie depth since Driedger is waiver exempt. It's basically an insurance policy.