When you're addicted to caffeine, you begin going through withdrawals after you go without it for so long (which sounds like it's about a day for you). You can either slowly reduce your caffeine intake gradually so the effects are less when you go a day without, or get used to having access to some kind of caffeine to cut the headache (I use excedrin for headaches, which has caffeine, though not all of my headaches are caffeine withdrawals
As to the weighing thing...you don't gain weight with water. Drinking water helps your body expend that water. If you deny yourself water for a day, your body is afraid you're going to go thirsty so it hangs on to all its liquids (water retention) and you would be a few lbs up from that. What time was each weigh-in? Same time of day? Is it TOM anytime soon? You wouldn't be gaining 3.5 lbs in a day, so it's most likely some change in how much food or water was in your body at that time. It's also possible your 220 weigh-in when was you were dehydrated, which at first (say directly after a work-out) might make you appear to way less.
As far as the commute, mine's not as bad but I know how it is. I signed up for the Presidential Fitness Challenge and am aiming for 30 mins of cardio 5 times a week. I started with WATP videos. I use them immediately after dinner and before I relax for the evening. Yes, I'm tired, but I find after I'm done I'm so glad I worked out and get a little bit of an exercise high that I feel much better. I also try to go walking at work whenever I can. Hope that helps.