saving money on food at disney is not all that easy...I think the vouchers are agood idea,,read about them on the budget board , first thread. I got mine at hotwire. wealth of info about them so you can decide for yourself.
If you do not mind going off property to eat ( like if you have a car)
you can go to
www.Restaurant.com and get money off meals there. you can get the certf. also by bidding on ebay ( usually save a few $$ that way) imo the $25 are better than the 50% off but since you have more people you could check out the menus listed for the rest. you want to bid for.
also we only eat really 2 meals a day and usually eat a big lunch at a sit down since the menu is cheaper( often by3- 5 bucks an adult entree and usually has at least some of the same choices..plus it is a good rest break. options are take granola bars or something similar for breakfast in your room if you do not need a big meal first thing. then make an earlier lunch ps and grab a counter snack type dinner. or eat a big brfst. late lunch and snack on something for dinner in the room. the Cm at wdw-dine can tell you the hours of each meal at each restaurant when you call.
this is not what some others think but...
imo since you are going in Jan. no way would I go back to the hotel mid day, wastes too much time since the parks close at 5-7 ( epcot later) and have found our kids did great with the hr or so it took for lunch as "down time". if it makes for too long a day just leave when you are done since it can take 45 mins each way to get back and forth from MK to all stars and then another hr to rest. you've lost 3 of the 8 or so you can spend at the park..just not worth it to us. plus in Jan.the heat and crowds do not zap you like it does in warmer weather
it may be too cool to swim for some days in Jan so if you really want to, do it on whatever day the weather is good for it since it may not stay that warm all week. other than that we have always had nice enough weather for short and tees ,a couple times jeans and sweat shirts but it can be cold ( in Dec. once got to low 30s at night)esp. at night so take stuff you can layer on and off as need be
I would definitly call now for Ps . we are going a few days later and I haven't had trouble getting any but are not doing character meals either. have in mind where you want to go and what day and time. they will ask you how many and where you are staying and stuff and give you a confirmation # ( take that with you "just in case" ) the number is 1407-wdw-dine
one thing to think about with character meals.. they are expensive and our kids were always way to excited to eat at them...so I wouldn't load the schedule with to many if cost is a factor since we always ended up paying for "snacks" later as well as the uneaten meal ...there is an cheaper ice cream social some like( never did that one myself) and always toontown and time for pix there but it depends on your kids a lot..some do not even like the characters! ( a 6+ ft Goofy can be a scary thing !!
most of all...
Have fun!!!!!
As far as making ressies or a PS as it is called here on the DIS, you can call 1-407-WDW-DINE when you decide which ones you want. 
