Well, the highest binned chips get the "K" tag, but the yield is so good, anything that says "3770" on it is top of the line. The "K" does have an unlocked multiplier which does make it easy to overclock. I do not really understand the aversion to overclocking. If it runs at 4.5-4.7ghz at stock voltage, then you just got a bonus.
Motherboards- just depends on the features you want and how much you have to spend. As far as manufacturers, at this point Asus is my 1st choice, followed by Gigabyte. I tend to avoid the "3 letter" boards for higher end builds due to personal experience. Asrock- hit or miss, but usually OK, but BIOS options tend not to be as polished as Asus and are usually "buggier" during the early BIOS revisions. Biostar- flip a coin. Things to consider, USB 3.0 header configuration, PCI/PCIE slot layout, power management, BIOS options, SLI/Crossfire support (if you need it). What size? Full ATX? Micro ATX? Depends on your case.
RAM- At this point 1600 DDR3 is the defacto standard for most builds. It is cheap, and performs well. The sweet spot, where latency and speed curves are USUALLY most advantageous is DDR3 1866 according to those brains who know. Personally, I never saw big jumps in performance going from 1600-2000 as I had to loosen up timings to compensate for the speed.
A good start is to pick a motherboard, and glance at the "Recommended Memory List" . See what memory has been tested with that board. Now, it isn't absolutely necessary, but it will give you a starting point. I like low voltage memory on Intel rigs (1.5V or 1.35V).
All the above is my opinion.......I could be wrong.
I am a retired Ford tech. Next to Fords, any computer is a piece of cake. (The cake, its not a lie)
3770K @4.5, Corsair H100, GTX780, 16gig Samsung, Obsidian 700 (yes there is a 700)