Welcome, welcome!
Like flots said; the straps on women cut BC's are slightly curved to conform w/ a woman's curvature. A man's BC may have the shoulder straps digging into your bosom, where as a woman's BC will curve around it. Just like clothes though, some brands fit better than others.
As for D-rings, I do sci diving in the Monterey area all the time and I've never had the need for more than 3 D-rings. I'm affiliated with UCSC, but know several divers who dove with the Humbolt Uni program.
Usually when I'm doing a sci dive, my slate is clipped to my shoulder D-rings (2 connections)
- flashlights are clipped to each shoulder D-ring
- meter tape to my hip or crotchstrap's back D-ring
- meter poles/quadrats are held in my hand or slid into my waist strap
- and anything else is jury rigged to clip onto my free or used D-rings w/ double enders bolt snaps; placement depends on comfort or space taken.
I've recently switched from a stock BC with 6 D-rings (2 shoulder, 2 crotch strap, 2 waist) to a Bp/W (backplate/wing) with 5 D-rings. But honestly between the two of them I've only ever used 3 for equipment connections (including SPG, SMB, reels, whistles etc).
Getting pockets onto your wetsuit also frees up space.
The trick is to get bolt snaps. It's far easier to work with a full D-ring if you have bolt snaps instead of plastic clips or carabiners. Stainless steel works best because it's not sharp and they come in varying sizes. I usually put small bolt snaps on items I use rarely and 3/4" or 5/8" regular sizes on everything else. Temporary gear is clipped off using 4" double enders and zip tie loops. Also clipping so the opening gate faces away from your body makes it easier to clip and unclip things from the D-ring.
Bolt snaps are tied onto items using nylon line/caveline or shock cord/bungee.
For double enders, I attach a ziptie loop onto my item and clip off the double ender to that and my D-ring.
BC's, of your choices you posted, I would chose another Zeagle. The LaZer has plastic clips holding the bladder to the BC. I've seen those break before which leaves your bladder flapping around a bit. Sci diving is notoriously hard on your gear, if not the environment, then the divers yanking your gear onto the dive boat (which usually doesn't have a dive platform I might add).
The Bare Curve looks like it would fit what you're looking for, however it's pretty much the same as the Oceanic Excursion 2, except for the womans cut and a few extra D-rings.
If you use the top shoulder D-rings your items are going to conflict and dangle in front of the lower one. The waist D-ring will lead you to dragging things on the bottom when you work substrate surveys (ie you'll have to be hugging the bottom). So honestly to hit that point again, you don't really need them nor will you find then genuinely useful.
BC pockets aren't entirely useful either unless you're carrying small vials or an RPC chain. Small vials can be clipped into a game bag, which makes it less likely you'll miss placing it in a pocket w/o knowing (therefore losing your data). RPC chains can fit in even the smallest pocket. So don't go picking a BC because it has big pockets, you won't find them as useful for sci diving as you might think.
You may eventually hear about buying a Bp/W (backplate/wing) system on this forum. Those are modular systems consisting of a separate plate, harness, and buoyancy wing that you connect to create a customized, personalized BC.
It's daunting to set up on your own if you've never worked with or seen one before.
They usually come with a crotch strap in which case I believe Humbolt's program requires you to have your weight belt outside the crotch strap or have a weight harness to allow yourself to quickly ditch your weights.
Feel free to google up "site:scubaboard.com Bp/W" to read up on it. And if it interests you, PM me and I can tell you more about it's specific problems that come into play when you're using it with a sci dive class/program.
Having said that though, I use it and plenty of other old and new sci divers @ UCSC are using it too. Although a lot of the new divers need to be talked to in regards to optimizing their system.......Keep in mind that you can't look at it as a package BC, which seems to be the trend in the UCSC program unfortunately.
Regs: Pick a first stage reg that is balanced so you're don't have to worry about your breathing getting harder as you breath your tank down. You don't need an environmentally sealed one for your area (unless you're ice diving), but I would suggest getting a diaphragm or sealed piston(Sherwood makes the latter). Reason being, when you're outside of the sci dive class in the world you may not always be able to rinse your gear after a dive, or if you're on an island like Midway, you never rinse your gear period. Piston regs have their inner workings very open to the water and this type of condition would surely have a bad effect on them. Diaphragms and sealed pistons have little to no inner workings exposed so will tolerate this better.
Second stage can be balanced or unbalanced. Although balanced will never ever feel hard to breath. Unbalanced may require some slight effort if you're really fighting a surge or trying to break past a high wave entry/exit.
