here are two books that may be useful: 1) A Field Guide to American Houses, by Virginia and Lee McAlester. It is the standard, and it has pictures of houses similar to yours under 'Prairie'. It also shows porch posts that come from the period which you might enjoy. 2) House Styles in America, by James Massey and Shirley Maxwell. They write for The Old House Journal. This is in color and will give you ideas of how the houses in the first book might look with different colors. Your house is stucco which would have been earth-colored (red, brown, tan, even green - all muddy feeling, muted) or white, sometimes gray, with the window and porch trim and roof verge board and rafters as accent. You have white window sash. If you can't paint them, you should always add that color into your mix when you are trying swatches. Contrast is fine, but the colors are less sharp, not like a Colonial (which could be white with blue trim - what you have now). The windows would be all within one color so that they read as one thing, not each piece emphasized. Also see if you can pick a color from your roof. It isn't particularly visible, but you want everything you have to add to the image. The square lattice at your porch is a good choice - more Arts and Crafts, 4-square, Prairie, than diagonal lattice which tends to look more Victorian. Changing your porch posts and railing system to something less generic and more period inspired would really change the feel of the house. The colors you show in your swatches are going in the right direction. The question is where to put what! Look at Massey and Maxwell's book and see what makes your heart go pitter-pat! Then copy and adapt. And try out your colors on the back of the house!

Paintguy hit the nail on the head. The key part is to make sure it's an EXTERIOR paint (sometimes referred to as masonry paint). I wouldn't bother re-mudding the whole thing, you can go right over the old finish coat. If it is textured, applying paint over it will cause you to lose some of the texture. Here is a link that might be useful: Stucco Trim Supplier

You don't need to wash the trim if you're sanding with a hand sander. In fact, why are you bothering to sand at all? That's typically not done or needed. However, to answer your question, you can safely use power tools outside in wet weather, as long as you're: 1) not in pouring rain, 2) not standing in a puddle, and 3) your extension cord plug end doesn't fall into a puddle. To be particularly safe, it would be a good idea to plug the extension cord into a GFCI-protected receptacle, which you should have in several inside locations and all outside locations, in a new house. I also presume that most of what you are painting is at least slightly protected by the edge of the roof? Humidity is not an issue, other than slowing drying time a little. It would be best to use latex primer/paint, as this is water-based, and will also dry faster in these conditions than oil-based paint. Unless you get a driving rain directly on the painted trim within an hour of application, you'll be fine. At worst, you might have to re-coat it if it got drenched. I think you are making this project too elaborate. Just caulk where you must, and slap the primer on when you get a little break in the weather; then paint. This should only take a couple of nights. And, if you've never caulked, here is a tip. Get a good quality PAINTABLE caulk (it should have a 30-50 year warranty). Practice a little bit. And be aware that you can do a really neat job by using a moist paper towel, or even your finger, to smooth the bead immediately after you lay it down. This will get rid of any irregularities and make for an unnoticeable caulk job. Just keep plenty of paper towels around to keep you tidy as you proceed. Good luck.

I don’t feel you have to match furniture and accessories to art or vice versa. It‘s a personal decision as to how you want the space to feel - art being prominent or room matching. My suggestion if adding lots of pillows is to look at inspiration pictures on Houzz and Pinterest to help narrow down styles/patterns/solids/size combinations - which is extremely important and not easy to achieve without a few attempts. The choices you provided for example will just feel lined up and being used for their color instead of as a design element. Adding a rug could also help bring everything together I would skip colored drapery for a calmer feel. Grey linen drapes on a black rod in winter and if wanting to lighten in summer, use cream or white