Sounds like a great eater!
For weaning the BT bottle I would do it gradually, I am not one for cold turkey on anything. You can read a description of what I did in this thread and also how another BW mummy successfully weaned that bottle tear-free and no upset to BT.
morning bottle still needed?(the initial question was about morning bottle but it was the BT bottle that was weaned).
I think that will answer all your questions about reducing the BT bottle, it will be gone within a couple of weeks so I wouldn't worry about the sudden switch to the sippy, he can take or leave his evening milk. Mine didn't take much of that sippy milk in the evening for ages then about a year of a 100ml or even more and then dropped it totally.
Supper can be anything really, crackers, toast, cereal, veggies, crumpet, pancakes, muffin (I bake sugar free), little pastries (puff pastry tarts - sugar free) as he has a very well balanced diet it doesn't matter all that much. I avoided fruit but only because I suspected it made him gassy after BT.
I have once of twice given mine a few drops (literally 2 drips) of lemon in a cup of water but I don't give juice or cordial at all, sorry can't really comment as we don't have any constipation issue here. Teeth wise if you give juice try to make it at meal times so he doesn't get an extra attack on the teeth.
If you have any more questions do ask, and good luck with the wean, I'm sure it will be fine
Do