You want the new fad? Great. Tear down that whole wall while installing a temp wall to support the ceiling joists that are carried by the masonry. Then create a big new header to carry all of that weight, with the associated point load piers. Then you you can create a wider, code compliant, firebox. Cheapest would be a manufactured insert rather than site built masonry as exists. An alteration of that level will not be cheap. Even for a supposed Pro contractor who doesn't seem to understand basic home construction better than an old crabby designer.

If you look to general standards youll get caught up in a long hotly debated topic. The topic is 2" as written in certain code. This means the finished height of the threshold or curb is to be 2" above the showers drain strainer. How people in California have curbless barrier free showers built is another drama altogether. Bypass the interweb and call your local Plumbing inspector for the most direct undebateable answer. A few things to look out for if you get stuck or bamboozled into a hot mop. Most hot moppers skip the REQUIRED preslope and most will mop over a treated stacked 2x4 curb. Both of which can be fatal in short order. I suggest you take your time and source and hire A proven tile professional and try hard to avoid the hot mop..

Flush mounts are held to a different safety standard than chain or rod mounted lights.

"Should I assume watering is only needed when the surface looks dry?" No. That is not going to tell you the moisture content lower in the soil level. And that could very well be an issue with a high PWT or excessively moisture retentive potting media. One of the most knowledgeable individuals I know with regards to container gardening of any sort (Al/tapla) wrote this summary of judging the need for watering containerized plants by using a 'tell' or a pretty failproof method of judging soil moisture levels. I have copied his comments below: "Using a 'tell' made from a wooden dowel rod works very reliably to 'tell' you what moisture levels are where it most counts. I hope what I wrote about using a 'tell' helps: Using a 'tell' Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support good root health, which is a prerequisite to a healthy plant. Watering in small sips leads to a build-up of dissolved solids (salts) in the soil, which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma. It creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor. In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water. Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'. One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue."