You got a lot of great info already but I wanted to chime in here. I know your doctors has probably told you to start solids a couple months ago, as did WIC if you receive it. it isn't necessary, breast milk is all a baby actually needs for the first year.
Juice be it alone or in his cereal just adds sugar, there's no real reason to ever give your kids juice when fresh fruits can provide all the nutrition needed without the extra sugar.
suplimenting with formula is probably not necessary, if you can pump more over the summer or while you are home, It sounds as though you'd like to continue nursing once school starts back up again. pumping in between feedings should give you plenty of milk to freeze.
as for a schedule, babies are people, really little people, but think how often you want a little snack during the day, and it may come on about the same time or it might be totally random, choosing healthy items is a must but if you're hungry you should eat, same goes for babies. nurse on demand, and spread out the two small meals he's getting now to like breakfast and dinner, then add in lunch and snacks as he gets older.
also skipping baby foods and just offering mushed versions of what you are eating is perfectly ok, just avoid added salt. it will help your child adjust to the foods you eat. and avacado is a GREAT first food, very soft and full of lots of good things.
good luck, you seem to be doing just fine, and it isn't a first time mom thing, you learn something new with each one, so keep asking questions and trying new things and just be the best mom you can be, don't stress it.