If you're gonna eat mayo use hellmann's canola oil mayo.. if you're gonna eat salad dressings use craft olive oil dressings such as their italian dressing. Try to use store bought stuff with canola which is high in omega 9 monounsaturated and avoid soybean oil which is high in omega 6 polyunsaturated.
You should be able to find these at wally-fart.
Hellmann's Canola Mayonnaise, 30oz: Amazon.com: Grocery & Gourmet Food
Kraft Salad Dressing, Italian Vinegrette with Extra Virgin Olive Oil, 14-Ounce Bottles (Pack of 6): Amazon.com: Grocery & Gourmet Food
Kraft Light, Original, 30 Calorie Barbecue Sauce, 16.25-Ounce Bottles (Pack of 6): Amazon.com: Grocery & Gourmet Food
If you want to gain mass you need to eat carbs.. I would not recommend milk in large quanitities because it has a high glycemic index. Small quantities are fine. I would also not recommend apple/orange/grape juice.. it's basically just sugar. Eat an orange instead (just one at a time)
Black beans (which are cheap at wal-mart and I really like) are my friend. I mix them with ground beef and mushrooms, mustard, neotame, onion powder and some low sugar BBQ sauce (kraft light original bbq sauce) and it's really good. Black beans have a low glycemic index. A banana has a high glycemic index. Also glycemic load matters, the amount of carbs you eat at one sitting. Try to keep your blood sugar from spiking above 140-150 mg/dl at ANY TIME if possible to prevent your type 2 from progressing. Space out carb consumption and eat several smaller portion sizes per day.
Don't be afraid to eat saturated fat, but avoid eating too much stuff with high levels of nitrates, like bacon and deli meats. Cook turkeys and refrigerate the leftovers.
You don't need to be eating lean beef or low fat cheeses. If you are exercising and fit, and also eating low glycemic, enjoy the fat. Also, the trivial amount of trans-fats in peanut butter don't really matter... enjoy whatever brand you like. I like the natural stuff, but I also like Jif, and sunflower butter and almond butters as well.
Also, I ate dozens of eggs over a period of a couple months and had my cholestrol checked.. rock stable HDL 70, LDL 75, VLDL 4, triglycerides 45mg/dl .. for me eating cholesterol and saturated fat does not raise cholesterol. Buying whole turkeys and chicken with bones and skins on is cheaper and you get more calories for your buck. The skin has collagen/gelatin in it and isn't gonna kill ya.