Size is the #1 problem with new chicken owners. Build it as big as you can afford, even if you end up not getting chicken fever, the ones you have will love the extra space. I built a 10x20' coop. Now I'm splitting it in half to make two, but I'm also making 4 more.
Here is a great article on chicken room:
How much room do chickens need
Ventilation is another problem. You can never have too many ventilation options. You can put up tarps or plastic to stop air flow for those times you need to. You can put shutters on the openings to open/close as needed. It's easier to put these in during your build then later.
A good article on ventilation:
Chicken coop ventilation
I use a horizontal nipple bucket for water and a bucket feeder for feed. Saved me on daily chores. I change the water once a week or less, depending on the weather. When it's really hot, I do it weekly or couple times a week to give them fresh water. My feeder holds 25 lbs of feed. It will last me at least 2 weeks, maybe a few days longer.
A link to both of these are in my signature.
I use the deep litter method and only clean my coop once a year. Some people use sand and clean daily/weekly. It just depends on what you want to do and what works.
Just remember that what ever methods you use for your chickens, you will probably be making a few changes to suit your setup. Just have fun and enjoy your chickens!