I think 3 days is a good minimum unless you're just people who go with the flow. If you plan to hit everything, 3 is good. 2 can feel rushed. I would do DL, California Adventure, and DL again or DL + Dinner offsite. We usually do 1 day of hitting each with plans to go on all the rides we like and then the final day is just to take things easy and enjoy the park.
TS meaning Trader Sam's? I would do it for dinner because it's pretty out of the way. If you're staying at the DL Hotel, it's right there. If you're coming from the parks, it's about a 10 minute walk. If you stay at DL or Grand CA, I'd imagine you'll get an easier time making reservations. We've never stayed onsite so I don't have much advice on that. Others really like Grand CA. We usually stay across Harbor at the Courtyard Theme Park Entrance since it has 2 queens, 2 bunk beds, and 2 showers for a much cheaper price. You'll get early entrance 30 minutes prior to opening but it's only a certain park on certain days.
We like to do the Fantasmic dining package so you can have a dedicated place to watch but it's just luck of the draw on where you sit. Blue Bayou is decent. You get a place to go sit after the meal that's usually a great view. I think we did Cafe Orleans where you sit outside and watch after your meal is over. We enjoyed the World of Color dessert party but it's a lot of food but the view is great.