If you really want to make a pattern fit three-dimensionally then it is possible but it is extremely time-consuming and tedious. I wouldn't recommend it but would suggest something like SketchUp instead. Also, something like shingles getting smaller as they get further away (ie closer to the ground) wouldn't really be noticeable at this scale. But it can be done and here's how:

1. Start with a new white layer and put a layer style of pattern overlay on it. Set the scale to what you need. Create a new layer, link it to the pattern layer then move the empty layer below the pattern layer then click on the pattern layer and merge down. This gets rid of the layer style and puts the pattern on it's own layer so that you can rotate it and what not.

2. Use the rectangular marquee tool and make a selection large enough to cover 1/2 of your roof. Hit edit-copy, then edit-paste to put this selection on a new layer. Hide the old layer.

3. Move this section over your roof and hit edit-transform-perspective = grab a corner, hold down the shift key, and pull it in a little bit, then click on the check mark at the top of the screen.

4. Hit edit-transform-rotate and rotate it to fit. Now erase the parts that stick out beyond the roof. Make sure that you fit it to just half of the roof. Duplicate this layer, hit edit-transform-rotate 180 degrees, then merge down. Duplicate this layer again and rotate it 90 degrees. For rectangular houses you will need to do more erasing. When done merge down.

5. Now do this for each and every roof.

Terribly, terribly time-consuming and really not worth it. I've done it and it sucks. Instead what I do is to make my buildings aligned to the cardinal directions so that the patterns line up properly, then do the "merge-to-empty-layer technique" to get rid of the layer styles, then rotate the whole building to fit the street. This goes 100 times faster but you do lose the perspective but, like I said, it isn't even noticeable at this scale. On an encounter map (say like a few huts) where the roof is much larger then this technique only has to be done a few times in order to do all the roofs needed so it's not so bad.

For what its worth, I think your map looks fine so far and doesn't really need that level of micro-managing.