BIG Post Warning!Hey Delta, your input will always be welcome! You know I'm a great fan of your work! :-)
Anyway, I'll try and respond.
1. Board: Thanks! I'd love to be able to do the cool graphics stuff you did with your board. My own 'card' options are very sub-par in comparison! So, the 2D+ plastic stuff was a way to differentiate my board from other's I've seen!
2. Character Development: I was a big fan of Space Crusade, back in the day! Hero Quest and the various other version of such games as well. I can see that Space Crusade would be a great fit for a board game version. This version is more inspired by Warhammer Quest - Map, Event and Loot cards, as well as vaguely similar game mechanics.
I have left the percentage idea in as an optional rule. Here's the page:

As you can see, any given skill is converted in to a 'less than or equal to roll'. It's a fairly simple inversion, and won't change much in mission. It can be modified - small target reduces required roll by 1, large target increases it, taking an aimed shot (no moving or other activations). I guess I was wondering if it would be easier to reduce this by a factor of 10, and just use the relevant SPECIAL. But as all this can be done between missions, and will happen rarely (only when characters level up would it change).
This keeps in-game rolls simple. There is just one dice to roll per test, rather than a percentage. When there are some weapons with multiple shots (Miniguns get up to 10), it keeps the dice rolls easy.
The question of development is trickier. I was going to give 10 skill points per level up. This could be spent on which ever skills you wanted. But, after each skill has been raised to a 10s number, then each level up will just be all on one skill to get it up to next 'rank'. That being the case, I may as well just use Perks which increase required 'less than or equal to roll' by one per rank of the Perk, like the Commando perk does in FO4. And them I'm really back to it just being an 'out of ten' value that could be calculated based on your starting SPECIALS...
3. Combat:Combat works by rolling to Hit on the table above based on weapon skill. If you hit, you automatically do the fixed damage each shot does, unless you roll a natural 1, which always hits and is classed as a Critical Hit (double DMG). A 10mm Pistol does 1 DMG, and Hunting Rifle does 2 DMG, etc. However, what changes is the number of Attacks Per Phase, or APP. The Tire iron in the loot cards above has an APP of two, so you can make two attacks per turn.
Damage Resistance offers a 'Armour Save', where rolling less than or equal to (>=) your DMG Res. will stop any DMG from that hit, but you can't resist DMG that is over double your DMG Res.
If you make no other moves of activations, you can make an Aimed Attack, which increases the score you need to roll >= by 1.
So, a Character with a Small Guns skill of 35 would need to roll >= 4, or >=5 on an aimed shot. A VATs attach can be made by expending an Action Point (these let you make special or additional activations per turn, but you get a fixed number per mission based on your Agility). Not only do you get to make an Aimed Shot, but you can target a body part. A VATs show will Critical Hit on a 1 or 2, and will 'cripple' the bodypart hit, causing the NPC to suffer a negative modifier of some kind (such as reduced movement, Melee DMG, or To Hit rolls).
In my test game, I found that this makes a party of 4 characters rather powerful. Between the team of four characters, there were over 20 VATs attacks available. Statistically, that's 4 critical VATs hits per mission - quite enough to all but incapacitate even Boss Creatures. NPCs can't use VATs - although some have Special Attacks than can cause crippling effects (Mire Lurk Kings can cripple heads).
I am quite, but not entirely, happy with the system. What it lacks is randomness. If a bad guy has 6 HPs, I know I have to hit him 3 times with a weapon that has DMG 2. Sure, a Critical might reduce that to 2 hits, but it is still largely predictable. If you need >=4 to hit, then with aimed shots you can reliably predict it will take 6 turns to kill the bad guy. That predictability removes some of the chaos and excitement...
Going back to Warhammer Quest, their Damage mechanic was to roll a D6, add your strength, subtract their armour value, and that was how many wounds they took. A roll of 6 would often kill a bad guy outright, where as a 1 would often do no damage at all. This added a layer of excitement. Yes, you had hit, but would you make a clean kill, simply injure it, or fail to wound? You couldn't predict it, unless the bad guy was so weak it was dead as long as you hit at all. My versions lacks that.
I could edit it in easy enough. Roll D10 to hit; if successful, roll D10 + DMG - target's DMG Res.
I'd need to up the NPC's DMG Res. scores (most are 0, like in the games), and reduce the APPs of many weapons, adjust DMG as appropriate. Alternatively, I could set DMG to be a variety of different Dice - D3, D4, D6, D8 etc. But I had hoped to stick to just D10s. Either way would add some unpredictability and excitement, but at the cost of making it less streamlined.
Much play testing needed! Need to get the set in better shape first!
4. Looting: This one is tough. Coming up with ideas for loot is easy enough. Most stuff is simplified. All food stuffs count as 'Wasteland Food', so no need to track which specific sort it is. Some foods might offer a bonus (Nuka-Cola gives you a cap as well as +1HP, for example). Armour is either 'body' or 'helmet'. Some items are useless, but add a bit of character - holotapes with a mini-story but no other use. Others give an in mission advantage (a key, or password that can help unlock things).
Loot is usually found inside containers - lockers, desks, crates, etc. Such containers can be searched using an Activation.
The issue I have is with actual 'Looting'.
I cannot find a way that I'm happy with in terms of Looting NPCs. It's such a prominent feature of the game - kill the bad guy, get the better gun. I don't want to lose that. But I can't find an efficient way to do it.
I thought of going full Warhammer Quest - Get rid of earning XP, and you buy levels with Caps. You kill something, you get a fixed Caps value for doing so, and 1 Loot card per Encounter event. But many loot cards are junk, food, or other mundane items. Exciting items are rare.
Or, I could try having NPCs have fixed Loot. If you kill one, you can choose to take the loot or not. If not, it is lost. Or maybe you have to test your Luck to see if the Loot is there. But fixed Loot isn't very interesting. Kill and NPC, get the XP, roll to see if you find the Loot item listed on their profile.
Or I could have 'Raider Loot' or 'Ghoul Loot' tables, etc - but that is getting a bit overly RPG and rather deeper than is efficient in a board game.
Anyway, sorry for the ramble! For those of you who took the trouble to read, thanks! I hope it gave an insight into my design process.