1. Yup, only concern would be if sank naturally and used a 7mm farmer john and dove regularly to 70+ft. As you dive dry, 35lbs is actually probably too big *width wise on the 7 inch tank*, but it'll be a non issue.
2. If your boss wants you to dive an X-tek tell him to give you one, if not, Dive Rite didn't technically invent the backplate, but they were the first to sell it and the STA, not that it means much, but there is certainly no reason to go away from them. The DiveRite wings are made in the USA if that matters to you, they're made up in New York, in a small shop that is actually pretty cool. No idea where SP is making their stuff, but likely not the US since they are a Jarden company it is likely in China.
3. I don't like one piece harnesses, I have a body type that is incompatible and I require a chest strap. I personally like the Dive Rite Deluxe harness which if you have any sort of skill with a sewing machine, you can make yourself. You could technically do it with a few slide locks, but I like it because it allows me to use a chest strap, but adjusts like a one piece harness instead of with pull straps.
Lots of people dive with one piece harnesses and if adjusted properly are great for most people even with drysuit rings, but I greatly prefer either a QD on the left shoulder or a chest strap which allows the shoulder straps to be that much longer allowing ease of entry and exit.
If you like the look of the deluxe harness, you need 8 2" slide locks, 6 D-rings *or 5 if you don't put a D-ring on the right hip*, a piece of 550 cord, and a small bolt snap. You can look at the picture below for reference.
https://www.divegearexpress.com/library/hogrigging.shtml
Follow those instructions, but the webbing will be cut in three pieces, one for the shoulders, one for the left lower shoulder and waist, and one for the right. Length of the webbing will have to be determined by you. Chest strap should be right at the nipple line, so the webbing will have to be decently long for the shoulders depending on how tall you are. The hole for securing the shoulders to the plate can be punched with a soldering iron.
The lower shoulder straps in this instance have one inch webbing sewn up over the D-rings in permanent attachment via sewing. This is obviously not required, and can be done with 2" webbing and a slide lock. The 1" webbing sewn in is better, but you have to know how to sew and have a machine that will go through 3 layers of webbing which most people don't have. The 2" webbing just won't bend around the D-ring quite as easily. Lower shoulders and waist strap go in just like a normal one piece harness following the instructions from DGX. You can put a pair of slide locks on the back of the harness if you don't want the shoulders to move, but if you dive in any other sort of exposure protection, then I wouldn't recommend it since you might need to tighten the shoulders up a bit. Make sure to leave plenty of room in the upper shoulders for length adjustment just in case, the second slide lock up top retains it, so it doesn't really matter how far back they go. The chest strap is just a loop of 550 cord around a small bolt snap. Video on how-to below
[video=vimeo;96850067]https://vimeo.com/96850067[/video]
http://www.diverightinscuba.com/cat...c1080-deluxe-harness-scuba-diving-harness.png
won't let me upload, but there's the picture of the actual Dive Rite harness. It's only $55 from DRiS, and probably the same from DGX, but if you already have all of the hardware, it's probably not worth buying a new harness.
hope this helps
Edit: Dan is probably talking about the Rec wing, which is abysmal for single tanks, but actually pretty good for small doubles. If the shop talked her into it, it's the shops fault not Dive Rites, the wing is good, just not in that situation. It now has a crossover in the bottom which some like and others don't for doubles/CCR diving, but you never had to go vertical, just slightly head up to balance the air out. Just leaning your head back was usually enough to equalize the air pocket. Some of them were horseshoes and that design was intentional to allow air packing for trim in unbalanced rigs side to side. I.e. the old canisters that weighed umteenmillion pounds.
The DRiS trianta wing is only $200 and is about 30lbs, which is closer to what you want for that size rig, and is very similar to the Halcyon Eclipse wing. The HOG 23lb and 32lb wings are also quite good at around $250. Voyager wing is probably not the best idea for drysuit diving because it puts most of the lift down around your hips, which is good for single tank diving with weight belts on, but in a drysuit the air in your legs usually tips you head down. Since you're a Dive Rite or SP shop, on the DR side I would recommend the Travel EXP which is 25lbs of lift, and will be plenty with a SS plate, and a drysuit. Would not recommend the Voyager, only because of the way it is built, which again, was designed for transpac divers wearing heavy weight belts, so it put the lift down around their waist to help compensate that. Halcyon designed their Eclipse series based on drysuit divers not wearing weight belts, so the lift is closer to the valve to help pick the valve end of the tank up as well as to counteract the moment created by light feet in a drysuit.