I'm still confused, but hopefully a little less confused than I used to be

I've been reading the saddle threads, and have garnered the following:
I should measure my sitbones sitting straight up (140 mm cc) and leaning forward (somewhat less). I should know the outer limits of my sitbones (about 160 mm). I probably need a cut-out, because I like to ride aero. I should stay away from saddles with a lot of padding. Is this about right? I have no idea if I want a "pear-shape" or "t-shape", or if I want a narrow or a broad nose.

I need new saddles - badly. I have a Selle Italia Trans Am XO (143 mm) saddle on my road bike, which seems pretty comfy, but only in the aero position. Finally figured out that's only when I scoot back, and because I then have a narrower platform. Sitting up straighter I start to ache after a while, and feel like I'm sitting on the edges.

I have an ancient stock Trek saddle which is pretty comfortable, but crooked, beat-up and mashed beyond recognition, so I think it's only comfy because it happens to be the right width. I've tried a couple of dh's saddles that KILLED me, probbaly because they were way too narrow. Felt like sitting on a hatchet

If anybody has anymore input I'd be happy to hear it. FWIW, I weigh 130 lbs, tend to move around a lot, and need a saddle (or is that 2?) for training and long rides on my road bike, and something not too elaborate on my mtb/commuter.

Can a saddle be too wide in back btw?