My oldest 2 are 4 and 3 yo. They are both drinking from a regular cup, and have been for about a year. I do have my children drink from spill-proof cups (a nice decorated cup that has his/her name on it, with a straw ) in the van, but not at home. At home, only open top cups are allowed.
About the pull-ups, I'd only stop using them when they are dry when he wakes up. My daughter "night time" potty trained well and rarely ever wet the bed. My son is not the same. He rarely ever wakes up dry. So, I'm tired of changing the sheets and smelling urine in his room, so I am starting to put a diaper back on him now, so that I have to change the sheets less. My opinion about the pull-ups is.....if he wakes up wet, keep putting them on him. I don't know how to "night time" train kids, so I cannot give you advice if that is an issue for you. I know that, personally, myself and my husband both wet the bed til we were older children, around 8 & 9 yrs. So, obviously, I don't know anything about night time training. If you, or any mothers that may read this post, know how to night time train, please let me know. I need to get this taken care of so that I don't have to keep putting him in a diaper.
Good luck and God bless!