I always loved those Gerber Little Entrees they have for toddlers, they are in next to all the baby food at the store. They have soft cooked foods, and my son loved eating them. He started on those around 10 months.
I would surely use caution with the jarred step 3 baby foods, taste one; they are nasty! Blueberry Buckle is the only step 3 food I used to give my little guy. Most babies don't like proteins that much, so harder things to chew in that category like chicken breast or hamburger are out of the equation (generally of course, all kids are different), and of course they LOVE anything with tons of starch in it; mashed potatoes, noodles, mac and cheese. Just as one of the other ladies advised you'll obviously want to keep an eye on him so he doesn't choke.
Don't worry about giving him cows milk versus formula, no offense to the other mom who pointed out it may not be a good idea, but I would like to see that study that says it raises risk of infection; remember back in the 50s and 60s and 70s if a woman couldn't breast feed babies were given whole milk with Kayro syrup via bottle. Nothing wrong with weening slowly either though. I would reccomend you warm the whole milk just a bit before giving it to him unless he is already accustomed to cold formula. He would take to it better, I used to get mine just a little warmer than "straight out of the fridge" because it shocked the poor kid the first time I gave it to him cold! Room temperature to start if he isn't already used to it. The difference between whole milk and formula, aside from nutritional components and refortification of necessary vitamins and minerals found in formula, is the baby's digestive ability to break down the bigger proteins and molecules in whole (cow) milk. My son's pediatrician has Matthew take a step down each year; at 1 and 2 he was on vitamin D milk, at 3 on 2% milk, at 4 on 1% milk, and when he turns 5 the doc says let him have skim. At varying ages, they need less fat from the milk because intake of regular foods makes up for that.
For protien, try vienna sausages. I haven't met a kid yet who doesn't like them, but of course they are shaped like hot dogs so cut them up. They are very soft and easy to gum/chew and of course a good source of protein. Anything else, green beans, carrots, even beets all well cooked can be given to him. Fruits of all kinds too. Remember that babies can do a whole lot of damage chewing with just a few teeth and their gums are very hard. I've seen babies with no teeth eat things that I found questionable!
Keep things cut up in small chewable pieces, not circular in shape, and remember that everyone has a gag reflex for a reason (meaning don't worry TOO much about choking, it can happen, but you shouldn't freak out about it every time he eats) and that local Red Cross chapters can teach you the heimlick manuever on persons of all sizes. Other than that, have a ton of fun with it! They make the most interesting and adorable little faces when they are trying new foods and seeing new things, and grow up all too fast!