If I'm looking up a product to be sent to a specific location for pick up and the pick up date says "today"......does it mean they actually have the item in stock?

Depends on item

I'm not sure, I suggest calling the location you wish to pick up your item

Ditto

It should but still call ahead first

Either it is in stock, or at another local Walmart that would drive it over that day.

That Walmart as it's called is a super store and any item that would require delivery would be in stock and would be done so the same day as purchased

Most likely