If you buy the kit for $1,149.00, the lens will be included. "What's in the box" might be because it's a description of the body only and up. Maybe.
Anyway, the lens will be there if you buy the $1,149.00 kit. It is a handy lens that matches the E-M5 nicely. Nothing beats primes, but the 12-50mm is very handy for the less serious daily walk-around use. I am very happy with mine, and am very pleased with the 12-50mm over the 14-42mm option. I've had both. Good luck!
Amazon sell mostly new gear, if it is NOT, it is advised on the page.
You also get a small flash, battery body cap, lens cap.
And .. you get one of the hottest small cameras around with acces to the best lenses going.
I use mine professionally, often in preference to my bigger pro gear.
The best info you can find is here at the BHPhoto site: http://www.bhphotovideo.com/c/product/842934-REG/Olympus_V204045BU000_OM_D_E_M5_Micro_Four.html . As you can see Olympus advertises a dust proof and splash proof system on their micro 4/3 cameras and Zuiko lenses. I would always suggest you verify with the perspective seller that the lens is the genuine OEM M.Zuiko lens. It most likely is (seems to be a package that Olympus sellers like to offer) but it doesn't hurt to verify this. As to water touching any camera equipment: Unless it is made to be submerged under water I would never trust my equipment in the rain and would immediately cover it up with clothing or my body. After all, if you're going to spend a Grand on photo equipment you need to plan to treat it with some level of respect when it comes to the weather IMHO.
http://www.amazon.com/camera-photo/dp/B002TSWTAA Note that these adapters are not compatible with autofocus or changing the aperture from the body. Also note that the 4/3 has a 2x crop factor. In short that means using a 50mm lens on a 4/3 is like using a 100mm lens on a 35mm film camera.
I did some research on the computer and this is what I found. Because any lens with stabilization that you purchase to use on the E-5 will be a different brand they won't communicate with each other. Therefore, if you have the stabilization on in the camera and the lens they will both operate, neither overriding the other. Based on what I read, they will cancel each out. You should turn one or the other off. They say that in lens stabilization is better for telephoto lenses and in camera stabilization is better for short focal lenses. Hope this helps.
Which lenses? In any event, the f-stop is printed on the lens, either on the barrel or the ring around the glass at the front. For instance, on my 12-50 mm zoom the f-stop range is 3.5-6.3 and is written "1:3.5-6.3". F-stop is the ratio of the diameter of the lens opening to the focal length, so on a zoom lens the maximum f-stop depends on the focal length the lens is set to. The longer the zoom length (20 mm vs 45 mm for example) the smaller the f-stop. Know that the scale is reverse, the more light a lens passes the closer the f-stop number is to 0. For example f/3.5 passes way more light than f/11. Do an online search for "F-stop" and you should find a reference to a Wikipedia article explaining it. Hope you like the camera as much as I do.
I don't know anything about the Sony, but I really like the EM5. While the menu takes some getting used to, (not intuitive) the results are outstanding. In camera stabilization gives me all the options of micro 4/3 lenses made by Olympus, Panasonic, and others. The list is long and getting longer as M 4/3 cameras become more popular. Hope this helps.
There's a piece of plastic covering the back of the camera, just underneath the shoe port. Remove the plastic cover. That's where the "metal piece" on the small flash inserts. BTW, the micro flash in kinda crappy. I recommend using a real flash if feasible.