Simple RPG Design WIP Thoughts welcome. Aiming for a 1-pager.

HP: Trying to figure out a base number that isn't too low or high.  I have an idea for a pegboard scale:
. . . . . . . .           . . .        . . .       . . .
       Base          Leather     Chain     Plate

Basically you have your base, and all the points up to whatever armour you have.  Its a cumulative continuum.  Certain hits would go through armour, others would be blocked by it

Monster HP: Based on Size/Challenge
Tiny:       Weak: 1  (Vermin swarm)    Tough: 2  (Kobold)  
Small:     Weak: 2  (Giant vermin)      Tough: 4  (goblin)
Medium:  Weak: 4 (Hobgoblin)           Tough: 5  (Orc/Gnoll)
Large:     Weak: 4 (Grell/Roper)         Tough 6 (Ogre)
Huge:      Weak: 8  (Manticore)          Tough: 10 (Giant)
Colossal:  Weak: 14 (Purple Worm)    Tough: 20  (Dragon)

Their abilities, attacks and such will make or break them as opponents.  I just don't want HP to be too high so battles are quick and decisive.  

Skills: Mutually agree on difficulty of the task, and roll on a d6? d8? Results could vary from smashing success to colossal fail. I am thinking of jumping a pit etc. for example. Could be a fun random element. XP could boost ability?

Movement: Not sure about this- roll based?  Base amount for everyone?  Running could be limited- maybe 3 or 4 tokens to turn in that would represent 3x base movement.  Or not, maybe its too needlessly complicated.

Combat:  Tricky for something quick, but maybe.... roll 1d8 to hit.  
1-3: Miss
4-5: Hit for 1 damage unless counter-roll parries
6-7: Hit for 2 damage unless counter-roll parries
8 is critical(automatic kill?)    

Counter-roll is simple roll to match or beat.  Shield and armour would give bonuses otherwise there is no incentive to have them.

Magic:
Priests: Access to all of spell list, limited 'mana points' to use them.  mana regained by full oput rest and prayer/meditation.  Not movement.
Wizards: Access to some spells, but others can be added after an adventure of they find a scroll/spellbook.  Spells cast based on points.  Points regained through total rest and study, not just 'not fighting'.

Artifacts and such could have 'charges' as well to prevent overuse and discourage collecting.

XP: from skill use (success (2) or failure (1)) objectives/missions completed, defeats of monsters and kills.  Tracked on a pegboard continuum as well.  past a certain number is new level/new bonuses etc.  teh number increases as you go up levels.  Caps at maybe L4-5.