Kizzmansky, chrpai and I don't often agree on a lot....but I'm going to echo nearly everything he's said.
-BCD: I'm an Aerospace Engineer. I like bells and whistles, I like all of the toys. If you get a BPW (good suggestion), do not put weight pouches or pockets or any other crap on there. No padding is needed, even bare torso. I've got a weight belt I wear all of my weights on. It's a freediver style weightbelt, rubber so it won't slip, stretchy so it compensates for depth, and tongue-style buckle like a normal belt so no slipping. If you're looking at going sidemount VERY soon, something like the Hollis SMS100 might be a good first rig to look at. I have a (and adore my) Hollis SMS100, but I'm (slowly) building a BPW just to have.
-Regs: I had Hollis regs and loved them. I still think they're some of the greatest regs I've ever come into contact with. However, part of Tech diving is servicing gear if it goes bad....so I've transitioned to Hog. My Hogs do as well as my Hollis regs did, and at a significant price difference. I've got the new D3/Zenith regs. The reason I sold my Hollis regs and bought Hog regs is so I could keep a single type of parts kits for all of my regs. I was about to buy deco and stage regs, and it would be so much cheaper to go with all Hog rather than all Hollis, and parts kits are available. I like keeping stuff to a single brand within the type, but I'll mix brands (all regs same brand, but not same as mask/fins/bcd/clips/etc)
-Computer: I have a Hollis DG03. $250 computer. Nitrox, 3-gases, mid-dive switch, up to 100% O2 AND it has a gauge mode. The only features lacking are He and CCR. Both of those are well out of my reach for now. Even when (if) I start diving Trimix, I'll be running my DG03 in gauge mode with cut tables as a backup to my Petrel (or whatever is the latest/greatest then). Computer technology is sprinting forwards by leaps and bounds. Would you buy a $1000 gaming computer if you weren't going to play video games for another couple years? No, you'd wait and get it then.
-Regs, cont: Go ahead and get a longhose setup with a bungeed octo. It'll make a lot more sense for the future. I'd also be tempted to tell you to get a couple of omniswivels, just because it reduces jaw fatigue and improves hose routing.
-Get a drysuit. Even in warm water, long dives get cold. Also, the comfort factor of a drysuit is immense. Get a p-valve with a quick disconnect, stay hydrated, and never leave your suit. When you get out, you're dry and comfortable no matter the water temps. I'll have a hard time ever diving wet again, even in pretty tropical conditions (I dove dry in the Keys).
-Lights: Definitely skip the gun-style plastic lights. China offers a bunch of decent lights for a good price through eBay powered by 18650 cells or the like. Intovas are great, and will make great backup/mask lights. I have a couple of little Hollis lights (LED 3) and love them. They're my backups. As far as a can light: I like the recommendation of the $250 light from the classifieds here on Scubaboard. It seems to be a great product at a great price. You'll find yourself diving with it on even if you don't need it, just because the signalling is drastically improved and it brings color back to underwater scenery. However, don't spend the money on a NICE can light until you need it. That technology is always changing, and if they release a new LED emitter or technology or batter technology or whatever, that's a lot of money tied up in a light you don't need.
-Budget: This has sparked a HUGE debate in a few other threads. If you're thrifty, cautious, and don't dive a whole lot, buying gear can be kept to a minimum. However, Tech diving is NOT CHEAP AT ALL. Having said that, I was able to start tech diving, buy most of my gear, do a lot of my training, and do a lot of diving as a college student with no job and a fiancee. If you're smart, you wait, and you buy necessities, you can spread the cost out and it stings a WHOLE lot less. Tech diving has a minimum price, but it can be as expensive as you let it be.
As far as DSS and nicer/cheaper BPW options: I wholeheartedly agree that simpler is better. However, that doesn't mean there's no point in buying nicer stuff. Tobin is a huge resource and will spend time making sure you get a setup optimized for you. He offers long and short plates and very high quality wings. The quality of the plate's finish, the quality of the hardware (stainless vs "stainless" steel, thickness), and wing finish all reward someone who buys the nicer gear. Hog, Oxycheq, Hollis, Halcyon, etc all make good stuff. Halcyon has the nicest, but I don't believe the difference in quality is worth the H-tax. My Hollis backplate is as nice as I could ever hope for.
If you do get a BPW, the brand might matter more than that. If you don't want to have to use a single tank adapter, some brands must be avoided (Halcyon) and some brands of wing/plate don't work well together.