What a thoughtful birthday surprise
One thing I would consider is that while Riverside may be about 45-60 minutes from
Disneyland with very little traffic, there are very few times when that works out. On weekdays, if DL opens at 8AM you'll still find traffic on the freeways at 6AM, and if they open at 9AM and you wait an hour to start out (leaving around 7), it's even worse. Even weekends can be bad. I'm a little farther out (about 10 minutes from the outskirts of Riverside), but if on Saturday we leave around 6:30 we almost never make 8AM rope drop, and that is using the toll lanes. 6AM on Saturday is when we have to leave for an 8AM rope drop (and sometimes that means changing plans and walking through DTD because security and trams lines are so long at M&F that even CMs advise walking in). On weekdays if you want to make rope drop I'd leave at 5AM and hope for the best (yes, there can be traffic at 5AM even on weekdays), and then if you are plenty early you can grab breakfast in DTD.
Coming home shouldn't be a problem if you are leaving after 7PM.
Speaking of breakfast, we usually choose not to eat that meal in the parks, either eating at home and bringing morning snacks, or getting something in DTD at Starbucks or Jamba Juice. Beignets at Jazz Kitchen Express would be a great breakfast and are a special treat that I wouldn't miss.
You absolutely can bring meals, they just ask that you use the picnic area right outside of the park. While some people don't care for it and choose to take up tables inside the parks, I actually love to use the picnic area when we take a meal, as it is quiet and lovely.
I see some recommendations for Blue Bayou as a special surprise, and I have to say that if you are on a tight budget, I would skip it. At the minimum, I would make the reservation for the last day of your stay so you can cancel it within 24 hours if your wife decides it isn't in the budget. One meal at BB could cost as much as QS for all three meals. The food is alright, but not something that will still with me as some of the best restaurant meals I've ever had. You have to accept that you are paying for the experience more than the food. If you do choose BB, go at lunch and have the Monte Cristo sandwich (but you can also get that at Cafe Orleans, for less, and it is still huge enough to share). I do think it is possible to pay a split plate charge and come away spending less.
I think one of the best value restaurants is Rancho Del Zocalo; you can split one of the bigger meals (like the half chicken) and still come away feeling like you had a full meal. Plus there are soda refills. Smokejumpers in DCA is also a good value as you can add as many burger toppings as you like, or even make a little salad to go with your burger. I can't eat the bun, so a CM suggested I order a hamburger patty as a side and then add toppings.
Flo's Cafe in DCA has one of the least expensive breakfast options, but honestly, it has been years since we had a good lunch or dinner meal there

Even last month we had a bad experience.
I know everyone is going to have opinions. I just want to say that any day at Disneyland is a great day, whether we can afford Blue Bayou and expensive souvenirs, or have to bring a picnic lunch and choose a pressed penny to remember the day. Take a lot of photos and have fun!