We FF DD and she was completely free of bottles by 12 months (which I think might be the guidance). We used the free flow tommy tippee sippy cups as again the guidance recommends free flow. But they do spill more than ones with valves. Most of my friends used ones with valves and their DC seem fine, so I don't know why there is a difference. The valve ones take more disassembling and washing.
I don't know if there is a reason to keep using bottles for milk. We did, but I guess it was partly habit. Perhaps a sippy cup is too fast flow to begin with.
I think weaning is the point when you can relax a bit, so apart from avoiding chocking hazards (whole grapes, cherry tomatoes, rounds of sausage, marshmallows, chewy sweets) you can experiment a bit.