A little late to the party here, thought I’d chime in anyway. First, about the rain barrels. There is something called a diverter, and the gist is that it diverts the first x minutes of rain into the ground, via regular gutter/downspout system. This washes the roof chemicals off, then collects the rest of cleaner water into the barrels.
Also, take a look at Earthbox self-watering container systems. These can be very low maintenance and also if you suspect contaminated soil or just want lazier gardening without weeding, etc, they work really well. I’ve used them for some years now with very little investment beyond the original setup. Global buckets DIY on youtube is based on the same principle and i’ve tried these, too.
These are less prone to small critters nibbling them, and can be protected from deer more easily. I often use floating row cover over them and it cuts down on insect pests. It’s a technology, though, so you need to follow the instructions carefully. I’ve gotten hundreds of plum tomatoes from one Earthbox in a season, just like you see in the ads. I started with a couple of these and got more. I have nine of them and get a lot of produce in a season. Not for potatoes or other root vegetables, but great for kohl veggies, lettuce tomatoes, herbs, chard, and more.
They used to have a much better website, but something happened to it and now most of the good stuff is in the archives. The Chicago rooftop gardens with Earthboxes were amazing.