Hi C.,
I too am a mom of twins, and my best friend(and my source of all knowledge) has early preemie twins like yours. The first thing you need to know is that you really can't do this wrong - go at the pace that is comfortable for you and your boys.
DO NOT listen to people who don't have twins when they criticize your schedule. IT IS necessary and almost every mom of twins thrives on it. To meet the needs of two or more babies you need to get them to the point where you CAN meet thier needs at the same time - it takes work and patience to get too it but my kids now eat and sleep better than most I know.
Solid feeding twins and still getting in all those bottles is a challenge. I know it is frustrating when everything just seemed to be getting better and suddenly your are feeding your kids 8 times a day again.
First know that practices have changed so many times over the years and there is no right way - I was exclusively bottle fed until I was one some kids start on solids when they are four months.
Your schedule looks perfectly adequate to me. It in fact looks exactly like what I did. I would maybe just let your little ones drink what they want from the bottle at 9 after thier solids and them go ahead and move it to 12pm or right before thier nap. They should still wake up hungry.
As for what to do with the menu. When you add in lunch I tried to give cereal and a fruit in the morning, cereal and a green veggie for lunch, and cereal and a orange veggie or fruit for dinner (they liked this better so I fed it at the fussier time). I also varied the types of grain for different nutrition. I used the www.wholesomebabyfood.com website for my tables of what to feed and when.
Some rules of thumb:
1) Formula is your main nutrition - as long as your kids are eating at least 18 oz they will have what they need to grow.
2) Cereal is like the formula of solid food - I gave it at every meal.
3) My Drs. Guidlines were to introduce one meal by 6 months, 2 meals by 8 months, and 3 meals by 10 months (add in 1-2 snacks by 12 months).
4) Don't worry about overstuffing your kids - they wont let you and if they do - they will throw it up.
5) As far as eating fruits vs vegetables. They generally have the same vitamins and minerals, fruits are higher in calories, vegetables higher in fiber. The most important part of offering both is not that your kids need it to grow (they get complete nutrition from formula) The most important thing is exposing them to healthy foods so they eat them later.
6) The next 6 months is just about teaching your kid how and what to eat - the formula takes care of the rest so relax and make if fun for all of you.
7) Don't worry about being behind - the more advanced the kids eating skills the more complicated your life will become. Thier nutrition will not suffer and finger foods are not neccessary until at least 10 months. Once the little ones start feeding themselves lookout trouble.