You are right, the Matoran mostly aimed for the Rahi's infected masks, and their main advantage is range. We rarely see a Matoran attack with anything that is not a disk, and whenever they wield a melee weapon it's usually something with reach such as a spear or staff.
Also from the MNOG: The Ta-Matoran guardsmen were helpless against Tahu even when they surprised him with a trap (clearly a Rahi trap of some kind), and Matoro was swept away immediately by the Muaka he tried to stand up to with a pickaxe.
An example of play-by-post using this system would be something like this:
Game Master: "The Le-Matoran with the infected mask noticed Takua standing there and immediately tensed up. The Ta-Matoran could see a dangerous gleam light up in his adversary's clouded-over eyes, and the green Matoran suddenly leaped towards him with surprising agility, arms stretched out in front of him."
GM makes a roll, gets 4. This is simply a "Yes" result.
Game Master: "Before Takua could react, the Le-Matoran was upon him, close enough to spot the rust flaking off his damaged Kanohi. His hands grabbed onto each side of the Ta-Matoran's blue Pakari...
Takua: Take 2 Physical damage, and remember to subtract your defense. You can't be certain, but it looks like this guy wishes to pull off your mask off. How do you respond?"
Player 1 (playing Takua): "There wasn't any time to react to the sudden assault, but Takua had needed to rely on quick thinking many times before. Almost by instinct, his arms shot up to grab his adversary's wrists and keep his mask from being pulled off. He then threw his weight sideways, attempting to shake the hostile Matoran off without hurting him."
Player makes a roll for Physical, applying whatever skills fit the situation for extra dice to roll. He lands on an end result of 6, which is a "Yes, and ___" result. Thus the GM should describe a bonus event occuring.
Game Master: "While the Le-Matoran was quite fast, he turned out to not be all that strong or heavy. In attacking blindly he had lost his footing, and Takua easily forced his grip loose and flung him aside. The infected Matoran stumbled and fell, landing flat on his face in the mud.
Takua: You took him by surprise! He takes 3 Physical damage and is now prone. You have a few seconds before he gets back up. What do you do?"
In this example, we have 3 posts:
First, the Game Master describes the situation, and sets up the start of combat. We assume something happened before that led up until this point, but it's not important to the example. The GM describes an action, and makes a roll. Based on the result, he describes the character taking some damage and gives something for the player to respond to. (Note that Physical damage was used here rather than Combat, mostly because they are wrestling with brute strength instead of using weapons to actually wound each other.)
Next, the player describes their response and intended action, and makes a roll for it. It's best to keep the outcome a bit open-ended. (However: In a relatively open-and-shut case like this it would have been fine for the player to describe the bonus event themselves, and as the GM I think I can trust you guys with doing that for minor stuff.)
Finally, the Game Master judges the outcome. In this case the damage is given directly by the roll, and the bonus result is inferred from the player's stated intention (wishing to push the attacker away). The new sitation has Takua in an advantegous position, free to do what he wishes.
And so the game goes back and forth between players and GM. If there were more players present at the scene, the GM might have stated the "He's prone, what do you do?" question to multiple people at once, or perhaps said something like "Jaller, the Matoran lands prone at your feet. What do you do?" if he wished to pull someone in particular into the spotlight.
Since we'll be playing on RPOL.net, the dice roller there ensures that the rolls are both public and not possible to cheat on.
Pros of play-by-post: More thinking time; taking a minute to calculate stats/roll results doesn't waste anyone's time; you don't have to be online at the same time and in odd time zones; flavorful descriptions are easy; you can scroll back and re-read past events; dice rolls and character sheets are recorded for easy reference and linked to in the relevant posts. Even things like splitting the party is possible, whereas in a live session this would leave half the group sitting idle.
Cons: More time between responses, so the speed of the game can slow down a bit. No face-to-face live talk. This list is shorter, but it can still be quite important.
Anyway, your character sounds good! Shame about the lack of cool visors.
Widgets mostly show up in Mata Nui Online Game 2, and do not have any set denominations. They are a lot like "gold pieces" or "coins" in other games. A couple of widgets could buy some resources like plants and shells, but they were mostly gathered by hand, and crafting was what you usually wanted to do. A bundle of nails was worth 5 widgets, for reference, but you could buy throwing disks for a pittance. It seems prices in the MU were mostly based on supply and demand, and negotiated for every deal.
When I say "pocket money" I imagine something of roughly equivalent worth to one of the other items on the list, so "pocket money" = "enough widgets to buy a hatchet or a bundle of rope". I left it a bit unclear on purpose.
Regarding language: Whatever the Matoran language is, it seems to be a universal language for most species in the universe. I've seen someone speculate on if the Skakdi language is similar in words/structure but uses different sounds/writing due to the Skakdi's mouths and guttural voice. It could also be that they prefer their own language, and use Matoran only when speaking with other beings. It makes more sense for Matoran to be the universal language (they are everywhere) rather than Skakdi (most canon Skakdi stayed around Zakaz).