ooooooooooook where to begin?
1) Have you played either guitar? Which one feels better to YOU? You're going to be the one playing it every day, so I feel that other people's opinions don't really hold much sway. FWIW I built a Rhoads last summer and it's VERY comfortable. King Vs are far too big for me, ungainly, can't play when sitting down, etc etc.
Plans can be found here:
guitarbuildingtemplates.com
guitarplansunlimited.com
google.com
2) Wood. What kind of wood do you like on your guitars? Read up.
http://www.warmoth.com/Guitar/Necks/NeckWoods.aspx
http://www.warmoth.com/Guitar/Bodies/Optio...oodOptions.aspx
google.com (note the heavy emphasis on search engines )
Ash, Alder, and Mahogany are popular, Maple and Walnut for necks. This is also a question of how well-sourced your area is, and how much you want to spend. There is no specific wood per-se for a metal sound. The more gain and effects you throw on your sound, the less important the wood is. Search the forums for plywood guitar experiments.
Strap button position is more important on how a guitar hangs. Your strap buttons want to be in as straight of a line as possible. Normal guitars balance well because the strap button on the horn is higher than the strap button on the butt.
3) Have you played guitars with EMGs? Have you played them through YOUR amp? The rest of your effects chain is just as, if not more important than your pickups. But, and not to be rude, you probably think gain is king. Play more guitars with different pickups. How many old-school mettalers played Strats with Seymour humbuckers? I remember this one guitarist who played a secondhand guitar with a stock Gibson pickup through an old Marshall Plexi, and even hooked up a Variac to LOWER the power of his amp. Crazy! (Yes I'm aware I'm beating a dead horse..)
What's the reasoning behind not having a neck pickup? If you REALLY just hate the sound of a neck pickup then you could drop more money on a GOOD bridge pickup. Look at:
http://www.swinesheadpickups.co.uk/
http://www.bareknucklepickups.co.uk/
4) A neck build is only difficult because it requires more specialized tools and greater attention to detail. That said, I built my first with a premade neck and couldn't have been happier.
carvin.com
soulmateguitars.com
Some of the best necks around. Soulmate by reputation, but I have a Carvin guitar and bought a neckthrough and they are the nicest feeling necks. Carvin, if you call them by phone, will give you plenty more options on necks than on their website. Basically any option they offer for a full guitar they will do for a neck.
Here's my opinion on inlays: They don't make you play better or faster. If you're just looking to pretty up your metal machine, though, go for it. Inlays require lots of time and offer basically no room for error. I would either get them done if you HAVE to have them, or go without, aside from simple dots.
Have you played a thin neck? I'll repeat what I've been hinting at previously: Get thyself to a Guitar Center and play on two or three guitars from every brand they have. Make a note, take a notebook and write down what you like and what you dislike, and you'll come further to finding out what works for you than asking people online. Compare a Tele to a Les Paul/355 to a JEM and find out if you even like a thin neck. I personally do not.
Do some searching on the forums, and you should be able to find answers to any question you have.