I'll try to answer these in one shot.
Happy to help, and I only wish I'd figured this stuff out sooner when I was starting out
I've found fishing structure is usually just about finding a few good spots and making your rounds. Often times it'll just be a slow time for conditions, or the current will make it less conducive to staying on a postage stamp sized boulder long enough to get a good drop. Thus, I'm usually looking to spend enough time out there to either show up when the bite is good or be there when it turns on.
FWIW, You pointed out something that drives me nuts! I don't understand why the topography of <1mi areas are so fuzzy. I wish I had access to that too. Most of my runs for deepwater rockfish are between 1 and 3 miles out.
That said, I would never ever ever paddle that far out alone.... Nor would my wife let me.
Not to rub it in on the garmin model, but I just found out yesterday that I can actually record my sonar to the SD card, bring it into an app on the computer and play it back with respective map points next to it. I'll show you what some of my spots look like (sans GPS of course
I can't speak too well (others here might be able to), but this is what I'm often seeing when I'm on a good rockfish spot. One of my best spots has an almost 40' dropoff (giant ridge) on either side, and we're usually getting bit in the fuzzy looking stuff.
You can find deepwater fishing (let's say south of the central coast, of course) anywhere between 210 and 170' in my experience. I cap the depth for QoL because I've never had to go deeper for good fish and drop/reel/drop/reel/drop/reel can get old fast.
There's another one here that's in 80' of water. This is a perfect Calico Sandy spot that yielded about a dozen hookups. You can actually see where my flat fall drops into the school, gets bit, and I miss the hookset before dropping back in.
I managed to haul up (For the first time ever, mind you) a little 1 pound red and a NICE lingcod yesterday on that 80' spot btw
YMMV further south where it's warmer.