Calm can mean anything... It could mean he's settling in well, or it could mean he's too stressed to fight back. You'll be able to figure that out as you go along and start learning his personality. I do hope it means he's settling in well, though.
When you offer food, have you tried "zombie dancing" the mice? Grab the mouse by the tail or the scruff of the neck (using tongs, of course!) and dance it in front of the snake. While some snakes are perfectly fine with you setting their meal on the floor, some need this movement to entice a response. Something to try, anyway.
If he hasn't progressed into full blue by now, I'm a little concerned. You may want to treat him for mites, just in case he isn't just soaking for an upcoming shed. Provent-a-mite is a great product--make sure you follow the instructions carefully. You can also try the Nix Mix (
http://www.cornsnakes.com/forums/showthread.php?t=52545&highlight=homemade+mite+remedy), but with one snake you wouldn't need so much.
One sign of mites, in addition to the soaking, is seeing drowned mites in the water dish. If it looks like someone sprinkled pepper in the water dish, odds are, your snake has mites.
They will also often soak to cool off, if the temperature is too warm. Make sure he has a good temperature gradient--there needs to be an area that gets down into the 70s for him to cool off. If he doesn't have a good, consistent cool area, it's time to rethink how you're heating him.
(Mites and too high temperatures can also be causes for refusing to eat.)
With feeding, if he doesn't take this time, next time, if at all possible, do NOT hold him before offering. Even taking him out for a minute or two can stress him out enough for him not to eat. Technically, you don't really need to change his water daily, either, so long as it isn't soiled--it's great if you do, but changing the water 1-2 times per week works fine, especially in a case like this where minimum stress is key and removing the water dish involves upsetting the snake.
Looking back at the picture of his enclosure... I'm realizing now that that last pic seems to show the whole thing? Would it be possible to get fake plants/vines in there to give him more security, and allow him to utilize the height of the viv, as well? Garlands are cheap at dollar stores, and craft stores will usually have sales, as well. Or, you can get fake plants at the pet store. String them across the enclosure a few times at different heights to fill up that empty space and give him more security and hiding places, and that will help a lot with making him comfortable as he settles in. It would also allow you to put his warm spot higher in the enclosure so the lower levels stay cooler, if you're using overhead heat.
Here's one example to show you what I mean. This is how I arranged my rat snake's 12x12x18" vivarium. That's part of a cardboard wrapping paper tube under the fake plants, which allowed her to hide inside the tube at any height she wanted. I heated from the top with a low-wattage colored bulb, with the hottest spot being way at the top of the tube/vines in the corner, so she had that one spot in the mid 80s and the rest of the enclosure at room temperature so I wouldn't have to worry about overheating. Her water dish also served as a hiding place, which is useful when you're dealing with small floorspace; it's one of those plastic dog/cat water/food dishes with finger gaps in the side and a hollow underside. As you can see at the bottom of the back wall, paper towel tubes also make nice, cheap hiding places.
Just some food for thought to help you further diagnose why he's soaking and not interested in food.
