We scanned through the US racers QA thread and these are our answers to some of your questions:
Pack weight - Talia 9Kg, Koby 10Kg. Including Water and food supplies.
Race preparation -
It is important to note that we were not sure we were "in it" until a few days before it started.
We took a personal P.E. trainer that trained us for multiple scenarios (cross fit training) - strength, stamina, balance and most importantly identifying breaking points and over coming them. We think it was marines methodology, but then again - they all claim that
Koby was in charge of equipment - and you only receive a vague description of what you should bring along with you (no they do not tell you to bring a headlight with you. some of them actually didn't
). We used "super trail" equipment lists to compile what we needed to take with us - as they are usually targeted at cross-functionality and low weight.
Equipment worth noting - we ran with dry food (also referred to as GORP) so we would not have to think about food. We had Talk powder, that enabled Koby to make the final cable car climb (not mentioned in the episode, but you can see it on his hands, coming down the second time) and a cord that doubled as a spare shoe lace and as a drying line for laundry.
As much of outfits as we could manage were dry fit, as in the Israeli version you do not know when the pit-start will be.
Equipment we wished we had with us and didn't think to bring along - protein powder, as Talia is a vegetarian.
Mental preparation -
This one is obvious - we watched, and analyzed, all US seasons and available international versions.
We debated learning Spanish but, unfortunately, decided that costs were amounting to "too much".