mmmm Your post could go in 3-4 forums. But I'll throw out some brief tidbits that could help, and you'll want to take particular interests to those specific forums (UI/Macro forum, HALP Armory/Spec forum, and this forum is the place to discuss the aspects of rotations and talent values in detail).
1.) Your spec is missing 7 points, but Frost is a fine spec and much of the backbone was there. Check out this talent calculator: MMO-Champ. It's a solid setup and has glyph selectors. You're quite right, there are few talents that can boost your threat as a tank like Bladed Armor can. For a Naxx epic'd tank it's about 160 AP per point.
2.) I'm less interested in a threat average, than whether or not you can hold threat from your raid team. If you can then you're doing alright, if you're losing threat then you need to identify where and when. Beginning of the fight, on adds, are people riding your threat on longer boss fights?
3.) Beyond spec, seeing your gear will be helpful to identify places where you can improve your stats for survival and threat. Dual wielding is entirely functional, but in its current state you want to be careful how you use it particularly with regards to the quality of your gear and the level of your weapons. Tanking weapons can get you extra survival values, but it can also flatten your ability to burst threat when starting/needed.
4.) I am an addon fanatic, and I modify nearly every aspect of the default UI though Blizz has been making some great improvements. You have Omen, that's valuable as a tank to be able to track your threat performance relative to the group. I use Bartender4 for making smaller highly customizable action bars. I use ag_unitframes to make clean, visible, and configurable frames. SCT is a great value for handling floating combat text, though I know there are many people here who swear by Satrina's sweet addons. For a DK I won't leave home without RuneWatch. It has a great UI that tracks rune CDs, RP levels, and most importantly disease durations (last night it was glitching which made me sad, but that's the first time since Wrath launched). The last addon I'd recommend checking out is Power Auras. You can create on screen glow effects to let you subtly but visibly track procs, health states, buff/debuffs on you or your target, etc. It's very handy for being able to keep your eyes up without feeling like it's cluttering your screen horribly. I could go on and on, but those are some great elements for your core UI.
5.) For macro'ing RS into your other moves your macro should read like this:
/cast Rune Strike
Names are case sensitive, but you can shift click them out of your spell book to make sure there are no typos. If there is no (Rank X) at the end of the spell name it automatically uses your max rank of the spell. As for sites, Blizz has an information page, but I'd imagine the macro forums here could offer just as much insight and with feedback.