Yep - I think regular dining plan is a great fit for you. Typically, people would use it as snack for breakfast, QS for lunch, and TS for dinner. It's also easy to switch it up. If you share some meals at QS and TS places here and there or have snacks for lunch sometimes, your credits can easily stretch to cover breakfasts too.
If you are very flexible over where to eat and what time you eat, there's usually same day reservations to be had. You do have to be flexible though as sometimes it just doesn't work out. Its very hard to do this at MK and DHS though - both have very limited table service restaurants that are always fully booked (except maybe Hollywood Brown Derby in DHS, which is a signature). If you decide to try for same day at these parks, go right when the restaurant opens and ask. I have successfully gotten 50s Prime Time this way. When I tried for Tony's Town Square in MK for dinner (not at opening though), I waited 1.5 hours. It really helps if you are willing to go to resort restaurants as they are sometimes less busy.
I would also suggest getting the Landry's membership card. You pay $25 and get $25 in welcome credit plus a $25 birthday bonus that is valid for the month of your birthday + 15 days after (both can be stacked for a $50 credit). You get a new $25 birthday bonus every year forever. My DH's birthday is in mid July. We ate in Yak & Yeti on Aug 13 and were able to redeem his birthday bonus. We used it for apps since that is not normally part of the dining plan. The best part - you get priority seating without a reservation at any Landry's restaurant - WDW has 3 on-site - Yak & Yeti and Rainforest Cafe in AK, along with Rainforest Cafe and T-Rex in Disney Springs.
Y&Y was soooo good. Especially if you like Asian food. We ended up eating there 2x over 2 weeks and it was delicious both times. Our new favorite.
Most don't sign their contracts until the end of the year. 99% of them will eventually be added. I wouldn't worry about it at all.
90% of them will have no problems with children or adults sharing credits. We have done so multiple times (and did a few times in our last trip). That said, in 2012, I was not able to share 3 credits between 4 people at T-Rex. I have been trying to pay attention but have not heard any reports about sharing there. I have not returned since. I have also heard that Via Napoli doesn't allow credits shared for their personal pizzas. I have stayed away due to these reports so am unsure. Every other restaurant, including Yak & Yeti, Sanaa, Whispering Canyon Cafe, Turf Club, Le Cellier, etc have all been extremely gracious about it. In fact, the best service I have ever received at WDW was at Chefs de France where the 4 of us sat down and only my 2 children ordered meals with child TS credits. We gave him a huge tip after that! I do usually tip based on all 4 of us ordering.
If the price is right - go for it! But I'm biased - I absolutely LOVE the theming of WL and it is my dream resort. The price difference shouldn't be that big as WL will have full
DDP for free included as a deluxe. Also, their food court has the BEST snacks - many unique things you cannot find in other resorts/food courts. And two QS options, both of which get great reviews. Whispering Canyon Cafe has really great food and is so much fun for kids. The BBQ skillet is always yummy - but also, my SIL had the absolute best fish of the trip at WCC.
I'm very price-sensitive though...so we stuck with SSR.