I let Lady sleep with me since taking her home at 8 weeks. However, I am very light sleeper and as soon as I heard her stirring, I would get up and take her out or use pee-pads. I used pee pads in the house with her until she was probably around 4 months old, but I also kept pee pads outside too so she knew where to go. I didn't have to "re-train" her without using the pads, i just slowly phased them out and she had very very few accidents inside. Like you, I get up at least once a night to use the washroom anyway, so when I got up I would let her go as well but it was generally only once a night. I kept this up until she was around 5-6 months. Now she sleeps through the night, but on weekends when I like to sleep in, she'll usually wake up around 7-8 to go pee then she comes back to bed.

And about the water, I don't think it's a huge issue to take away water an hour or so before bed time. If she drinks a lot during the day I doubt you'd be dehydrating her or anything...