Lots of good info, Kim. Here is my (non-expert) take on soaps harming your plants. Washing machine soaps: I have been watering with my washing machine for the past 3 years. The 1 st year the hose sat in the same spot in the front yard where I had planted some aspen trees. People commented on my "jungle" in the front yard. The baby aspens grew, the native grasses grew thick and tall and some wildflowers, I did not plant, appeared and all of this became a 10 foot diameter wildlife habitat. When I would go out to weed, I would find rabbit tunnels in the long grass and baby horny toads would come out to see what I was up too. I buy the cheapest liquid laundry detergent on the shelf. As long as it has no added bleach. If I want to bleach a load of whites, I buy a bottle of bleach and add it to the wash cycle. This water is routed down the hill where we have nothing but weeds growing. I figure, the cheaper the laundry detergent, the less harmful chemicals the manufactures will have added to the product. Shower Soaps and Shampoos: This stuff is tested to be safe for humans, so will it hurt plants? Probably not. Dish washing liquids: Here again, the cheaper the soap, the less nasty chemicals have been added. If it's safe for human skin, it's probably safe for plants. Automatic Dishwasher Soaps: This is one I have no experience with. I do not own an automatic dishwasher. But, I would suspect, that since the soap does not contact your skin during washing, the manufacturers have much more leeway to add caustic chemicals. I have not lost one plant to gray water watering in the last 3 years. My roses are happy, my rhubarb is huge and my baby aspens have outgrown their deer cages.

Once you landscape, you should solve most of your water problem. Adding exterior water proofing and drain tile around the entire foundation to exit on the down hill side will solve the rest of the intrusion into the crawl space.There really are no shortcuts in dealing with active water intrusion into a crawl/basement space. Preventing the water from entering is really the only sure way to maintain a dry space. As for the radon abatement, there are lots of solutions. Passive abatement is the least expensive long term. That means installing a grid of drain tiles(holes downward) and a stand pipe(extending to a height above the roof) under gravel. Then the plastic you mentioned and pour the concrete floor. The passive system is done without the concrete, with the plastic sheeting glued to the foundation walls and any pipes. Pouring a floor over it is fine., but the sealing is still very important, as concrete alone will not effectively seal against the gas. Which is forced from the earth naturally by pressure in the earth. Even though radon is heavier than air, the passive system does not allow the gas anywhere to go save into the piping and eventually up the stand pipe and out into the outside.

There are a number of ways to create a ceiling under a deck to create a dry space. The simplest are the ones that come as a system that you attach to the underside of your framing, like this one here: https://www.zipupceilings.com/zip-up-underdeck/ There's another system we've used but I can't remember it off the top of my head. You can also use 4x8 sheets of AZEK pvc trim lumber, using shims to pitch the water away from the house, mounted under the deck. There's also a system called rain escape (I think) that goes down on top of your joists BEFORE you install the deck boards. In all these options, you're pitching the ceiling away from the house (typically). There's a gutter attached to the inside face of the beam, and then a downspout attached to one of the posts. As far as best price, focus more on where you'll get the best service if there are any manufacturer issues. Local lumberyards or building supply yards are the only places I would ever buy composite decking.

Whatever you decide, keep in mind: you can do almost nothing from the inside. Let me tell you a story. I have a friend with a small 1920s home that had the same issue. They got a quote for $12,000 to dig up the foundation around the house, seal the foundation from the outside, and put in a gravel filled trench drain with sump pump around the exterior of the footing, and then backfill with proper drainage material. That sounded like too much so they started pick poking..... They had the interior wall "sealed." That didn't work. Interior sealers can't resist hydrostatic pressure. Then they had their gutters redone, and that helped, but the walls would still get damp with prolonged periods of rain. Then they paid someone to cut back the cement in the basement and put a sump drain around the interior foundation. That kept the floor dry, but did nothing to dry out the walls. They've had a few more "small" solutions done. Some have helped a bit, some not so much. Want to know how much they have spent now? $20,000 total, and they have STILL not dug up the exterior of the foundation. If they had just done the right "expensive" fix from the beginning they'd have saved a ton of money and they would probably have a dry basement. Also: that kind of work would be a general contractor, preferably someone who has home building experience and knows what a properly drained footing and foundation look like from the outside.