1. How do you execute these? Now this is a very complex question, since each movement has a different transition....so to keep it simple, we can start with simple Low Block (Ha Dan Mahk Kee). Does the blocking hand cross your body to opposite shoulder? Above or below chambering hand, plam up, palm down, palm in? Does it twist on the way down, once you get there, before it moves, etc...
There's a complex answer to that, because it involves so much. In fact, one of the first things I usually try to teach a new white belt is how to walk (in chungul jase). One of the central tenets of ITF TSD is "pick up your feet;" there are only a very few exceptions (palche so, some stance-changing moves with no step) where we drag any part of our feet along the ground as we walk. The basic walking step is this: from left-leg-forward, bring the right knee straight up to the chest, keeping the left knee bent at the same level, and step forward with the right foot into right-foot-forward. This goes for all stances: chungul jase, hugul jase, and even sometimes keema jase (ex: when doing weng jeng kong kyuk, as in the middle sequence for gicho hyung sam bu). No matter what, the knee comes straight up to the chest.
This has a few reasons behind it. First and foremost, you're avoiding someone sweeping your front leg (if you're stepping forward, you're not in a position where your back leg could be swept by anyone except Dhalsim). Secondly, you can ahp chagi very easily from this position. In fact, you can do just about any other kick just as easily from this position. Thirdly, it's easier to focus on landing hand and foot at the same time if the foot actually has to land. Fourthly, you're much less likely to stumble forward with your move; you'll have purpose behind each movement. Control of movement means better control of power. Also, you want to make sure that you're using your hips to snap into the move as you land. For example, in the first moves of pyung ahn e dan/sam dan/sa dan/o dan, you bring your knee straight up first and then use your rotation to drive the block as you go to the side. Going forward is the same story. You're not going in a 90-degree angle, but you still bring your knee straight up first and then rotate your hip to put power behind the move as you step down. You never bring your knee out to the side.
Now, the hand part. If you're doing a crossing block (ha dan mahkee, sang dan mahkee, ahneso pahkero mahkee, et. al.) you cross with one fist up on the opposite shoulder, palm facing inward, and the other fist punched straight down in front for protection. Your elbows should be on top of each other. Depending on which block you're doing, the up hand may be the blocking hand or vice versa (low blocks come from above, middle/high blocks usually come from below). The aim is to keep as much of your body protected as possible. What about the head, you say? This is most apparent in inside-outside blocks. When you do the block, you don't stay straight forward. Your hands stay in the same position, but your hips rotate your torso, so that now the fist on your shoulder is protecting your face. Similar story for high blocks. In a low block, you probably don't need face protection if you're blocking it low.
Knife-hand blocks are more complex. We used to do middle knife-hand blocks by bringing both hands to the hip first, but that led people to stop using enough waist twist. So now the opposite hand (the one that will be in front) comes to the hip, but the other hand goes behind the back, palm facing outward, so you have to put rotation into it. Low knife-hand blocks are similar: the hand that will be in front comes to the opposite shoulder, facing the neck, while the other hand winds up behind the back, palm outward.
I'd go into detail for each and every move, but that'd be exhaustive in more than one sense of the word.
2. What do you think about these moves? More abstract question....are they all hidden movements? Ways of encoding more complex ideas...or are they what they look like, simple chambering and throwing of the technique to get power, speed, etc.
Yes.
That is, both. A low block can be used effectively to block something low, just as a high block can be used to block something high, and a soo do attack can be used as a chop. They can also be applied with the more hidden moves, such as catching an opponent's hand, throwing, et cetera. Each technique has various levels of hidden opportunity, and it's up to you to decide how far into that you want to go. You could spend your whole life researching every minute detail into what a hyung might encode, or you could just do the moves on their surface and supplement that with learning how to throw, grapple, and lock. Or you could split the difference anywhere in between. Both inform each other.
Tang Soo!