sorry, just trying to answer quick...but STOP stressing...if he's eating and gaining...GREAT..but I do agree, time to get him on some more "table" style foods....
1) I personally do not feel juice is necessary...FRUIT is, water in a sippy along with it! If you do choose to start juice, I would portion 1/10...meaning 9 parts water, 1 part juice.
2) Cheerios should be fine. I would put give them dry on the highchair. It's also a great tool for learning dexterity.
3) Are you talking the individual servings of yoghurt? I would open one and put a couple tbsp's in another bowl. Save the rest covered for the next day.
4) Toast fingers...Toast a slice of bread, slice long ways. I personally preferred to cube.
5) ANY fruit that you have checked for allergies you can give him. I preferred to cube roughly the size of a pea. Grapes are a choking hazard, so if you choose to give them I would quarter them in slivers. (stay away from "round")
6) Crackers are a tough one, a lot of preservatives in them. Any baby style cracker or whole wheat, again just watching size.
You mentioned the cheese. I would cube hard cheese *cheddar, mozzarella and serve them on the train along with cheerios.
He can try regular pasta cooked soft, placed on his tray, we found penne, cut in half and rotini really successful.
Babies gums are rocked hard, and stronger than they look. My dd was on table meats with only two teeth...
Just watch the sizes and allow him to explore the food with his mouth. Use the appropriate language with him too, such as, chew babe, chew. If you find he's struggling with a piece, encourage him to cough, sweep his mouth if necessary, but DO NOT panic....he's watching you...Encourage him as he munches!
Good luck, again DO NOT stress....
HTH's! (sorry was typing fast...)
Marie