1. I have my entire family outfitted with Enos. The only reason I would say to go with a different company is if you are only going to use it for camping and nothing else, which I would suggest a Hennessy system. I like the Eno because it offers flexibility to just hang around the yard or where ever else with out the whole tarp system.
2. I would suggest a Doublenest. The extra room is nice to have to have by yourself sleeping (more room to adjust position) or to have a guest when just relaxing. I have a Singlenest for myself and have often contemplated buying another Double. You really aren't gaining anything with the Single other than minor weight savings, and if that's the case then you would go with the Sub7 to maximize weight reduction.
3. The Eno rainflys are convenient. I have the Dryfly, which I bought before there were more options, and it does take some practice setting up correctly. You will set it up nice and tight but if you run the straps through the suggested holes, when you get in the hammock the straps will put pressure on the fly and cause it to go slack. I think the Profly is a better option (my buddy has one). Mine did rip at the hole for the hammock straps over time.
-If you don't have a bug screen, wrapping the sides of the hammock over is a decent way to keep them away, especially if you have a little bit of weight in the pouch.
-If you go with Eno straps, get the Atlas system. The traditional Slap Straps have limited hanging options. I actually prefer just getting two 15ft sections of 1" tube webbing and tying a permanent loop on one end of each strap, wrap the strap around your anchor point and pull the tag end through the loop, then do a quick removable knot at the exact point you want on the strap for a perfect hang every time. I don't know the name of the knot for the midline loop but it's easy enough to figure out, and webbing usually unties easy enough.
-I have 3 months straight experience living out of the hammock while hiking the AT and countless other trips. It's the best way to sleep. Most nights if I'm not concerned about rain I don't bother with the fly, camp is set up in minutes. Right now I use a Klymit Static V sleeping pad in the hammock because it has wings on the side of the hammock that can fold up and fits into the Singlenest nicely (its super lightweight and packs down to almost nothing as well). I am comfortable down to freezing. An underquilt is pricey but by far the best way to go to stay warm.