I could be wrong, but as far as I know DCC equipped engines can also run conventional dc control (ie using speed control from a transformer). You wouldn't have the command control or sounds I assume, but you should be able to run those engines in conventional mode if you wanted to. Lionchief might be easier for you since it involves no special wiring (basically just need a power source to keep 18v at the rails) and a simple remote control.
As far as moving goes I can understand that, one way would be to build a layout easy to take apart (for example, use foam insulation board on top of foldable tables or something similar) if you think you could be moving in the short term. It might not be a detail scale layout (which I would hesitate to build if I thought I was moving anytime soon).
As far the flooding goes, I obviously don't know how had it is. One way would be to build the layout high enough off the floor that water wouldn't conceivable reach it, but I have seen houses flood where the basement is floor to ceiling in water (in my house, it is groundwater that would cause it, and wouldn't get more than a foot or 2, I have a french drain system and a backup generator for it. My take on that is it is easy (as I know too well) to focus on what might happen, and with the screwy weather we have all seen, it isn't hard to think like that, but in the end might be worth the risk
Another thought would be if there is another club nearby, like an HO scale club, join it and through them learn about DCC, or maybe even find someone through that willing to teach you. I understand being overwhelmed by technology and the like, I work in tech and sometimes reading what I do about Legacy and DCS on here I wonder just how great it is, given the things people report about it, issues with engines, etc....but then again, it is fun to learn new things, too (and I am not dismissing that you are older, I am prob younger than you by more than a bit, but I already feel that at times). Lot of people work in one scale at a club layout and have their own at home, nice part is the HO club could fill your need for scale modelling on a bigger scale, and your home layout would be fun with S gauge trains.
