For future reference, if you want to take a picture of your town map, tell Isabelle that you want to demolish a PWP (you don't have to demolish anything). The map will move to the upper screen and you can take a screenshot.
D5 in the top left box? So, your river starts high in the northwest corner, makes a sharp and narrow oxbow in the middle of the map, and your river enters the ocean in the mideast, correct? I can't really make any suggestions on whether or not your map is "bad" or "good", it really depends on how you want your town to be... If you think that you can't work with the map, then reset. A lot of people here will be happy to hold your stuff as you reset your town, by the way, so you don't have to lose all of your progress. (^^) I have A1 in the top-left box by the way, which I think most people would consider to be a terrible map, but it works well for my town.
You can't arrange villager houses that have already been built, unfortunately.

Here's how to plot-reset:
On a day that a new villager is moving in, go through the process of creating a new human character (do NOT start the day with a character that already exists). After you set your tent down, walk around town and see if you like where the new villager has plotted their house. If you don't like it, reset (new character isn't saved) and go through the process until their house spawns in a place that you like. After it sets in place that you do like, finish the tutorial and save. Afterwards you can delete your new human character.
Some tips on plot-resetting:
- You can set down PWPs in areas where you don't want your villager's house to spawn.
- If after a long time, your villager's house keeps spawning in the same locations, close your game. When you start it up again, the villager should start plotting their house in different locations. I'm guessing this has to do with reloading the game's random number generator or something.
- It can take a long time to get that villager into a perfect area. Spending hours, days, even weeks plot-resetting is not unheard of. I'm not too picky, there isn't an exact spot I'd like the houses to land on, so it doesn't take me an hour to plot-reset.