This is super exciting to me, kasslloyd, because I've spent the last year relearning electronics (from a few courses in university) and building remote hive monitoring equipment!
I'm never going to be able to cover everything in a post like this, but check out www.hackerbee.com and maybe send me an email at my username @gmail.com as I'd love to chat on the phone. I'm by no means an expert, but I'm about to deploy a system that sounds very similar to yours in the next week or two (minus the temp sensors, although I toyed with that idea).
I've also been working with Hydronics (at the Instructables link) to revise his bee counter design. Basically, I just designed it to pulse the LEDs only while their corresponding sensors are being read. That allows a massive reduction in power consumption (important since I have to run my sensors off a solar panel and battery)! I have a prototype board assembled that I think is functional, and once I've found a couple hours to verify it's working, I'll be ordering a full-length board.
Anyway, I built my prototype bee hive data collection around an Adams CPWPlus220 scale, but it's much too expensive and doesn't do exactly what I want. I've got it logging 2 temperatures (one will be in the hive and one to measure ambient temperature) as well as weight, and it will send the data back to the internet via XBee radios. My bees are coming this weekend, so I'm just doing some final testing, but the system seems to be running reliably in my lab. You can see the data output at Channels - ThingSpeak IoT
Finally, starting in June, I'll be putting together the pieces to design an open sourced bee hive scale that should interface nicely with Arduino. It will simply include three load cells, an ADC, and a cheap little microcontroller, so I'm hoping to put it together for under $75 (under $50 if I can make more than a couple). I've published most of the app notes that I've used to design the system on my blog, so you can learn most of what I know. I'm not sure it'll be the most accurate, and I KNOW it won't be the best engineered, but it'll be as cheap as I can manage with a target of a 0.1kg accuracy (hopefully including temperature sensitivity and drift).
Eventually, I'll get my existing, working system documented -- hopefully within the next couple weeks as I work on installing a solar panel out at the bee clearing and get the scale running in the field. Then I hope to get a working prototype of the low-power bee counter and build another hive scale prototype around a cheaper custom scale that uses less power, and interfaces nicely with Arduino!