Elle,
Thanks for asking the questions, I haven't really looked close at my camper attachment recently except to check turnbuckle tightness. I just crawled under the truck and poked into the turnbuckle camper access doors and am happy to say that everything is still straight, tight and good to go. We now have 40,000 miles on the truck with the camper and since I replaced the bolts at the camper with grade 8's we've had no camper attachment issues. We don't use our truck as a daily driver so most of the miles are on trips which consist of highway miles driven to our destination and then dirt and 4wd roads. At this point we have thousands of dirt miles on the camper. So to your questions:
1. I just checked and the picture is of the front passenger side and yes the Superstrut (SS) is oriented parallel to the long side of the bed.
2. Cross bolts are 5/16 x 2" long. Probably got the bolts at Home Depot. I went with grade 5's for the crossbolts because the shear strength should be sufficient to hold the load. Grade 8's could not hurt though, virtually anything is better than an eyebolt. I used nylock nuts or red locktite on every nut.
3. The SS is 1&5/8 x 1&5/8 x 6". I got mine from a now gone metal supply shop in Reno, however, I just saw it at Home Depot in the fastener aisle with the other steel stock.
4. I drilled the side holes in the SS which comes solid on the sides. FYI, the reason I used 2 crossbolts was to ensure that the turnbuckles would fit, I didn't have my camper when I mounted the SS and wanted to be sure I had some flexibility in mounting points.
5. 2x8" in the front and 2x6" in the rear. I wanted to spread the load out more in the front because the camper loads the front attachment points more. I used some simpson tie straps that I already had, they are about 3/32" thick.
6. As installed and tightened the forged turnbuckles are 12" long, they could be adjusted down to about 10" and up to at least 15". I got them from Fastenal which is also a great source of bolts and nuts. I tighten them by hand wearing a glove and don't use a tool. They should be snug with no movement but don't overtighten or you could damage the camper. I don't know how ATC sets up the attachment at the camper, make sure that there is a metal reinforcement plate in the camper, FWC didn't have this for many years and the attachment bolts were pulling out of the campers.
7. Everything is looking great.
I've got to say that I think the factory setup with eyebolts is a really crappy design. I'm sure it works for many folks who bought the camper for its light weight and low drag but who don't venture far off the pavement. If you go offroad and boondock like we do it is a recipe for failure. Our preferred camping is many miles off the pavement and nobody within miles of us. We sometimes go a week or more w/o seeing another soul. Have fun with that camper!