I would say do whatever feels right for you. I've been doing C25K for 6 weeks now, and usually I do one run every other day with either dance or weights in between because those work my muscles differently so I don't get fatigued. That being said, one week I felt quite tired, and did just one run that week until I was feeling better, and this week I have done 4 runs in a row because I feel really energetic. So, if you feel tired don't put pressure on yourself to run (just remember to get back into it when you feel better) and if you want to run, run! It doesn't matter if you ran yesterday!
Regarding drinking when you run - keeping well hydrated will actually stop you from getting cramps, but when you drink is down to personal preference. I like to drink plenty before I run, and plenty when I'm done but don't really remember to drink when I'm running. As long as you replace the water you lose somehow, it doesn't really matter.