This question is of relevance to all who wish to collaborate on the Old School Adventure Guide
Question 1: "Should character level lead to an increase in ability in certain actions or should species and ability scores determine ability in a certain action, independent of level?"
As an example, I'm thinking particularly about such things as breath holding time, and broad jumping distance here. The rules I have outlined previously suggest that level matters.
Breath holding time in rounds = Constitution + level
Broad Jumping distance = Level + Strength bonus + Dexterity Bonus + 2d6
One could easily design rules that might be independent of level:
Breath holding time in rounds (minutes) = Constitution / 3 (rounded up) as the Dungeoneer's survival guide does.
Broad Jumping distance = 4 (dwarf) + Strength bonus + Dexterity Bonus + 2d6
Broad Jumping distance = 6 (human) + Strength bonus + Dexterity Bonus + 2d6
This is important as well for rules design because, once level is added, the tendency by necessity is that a level 1 character often has ability in that action less than a modern human, but at high level they are likely to exceed a modern human.
To answer question 1, I think we must first answer Question 2.
Question 2: Are we creating rules for heroic fantasy or rules for the simulation of a world that obeys Earth laws as close as possible, within an imagined fantasy setting?
I was watching SG-U episode 3 (it's ok, nothing as good as BSG), and the characters venture onto a desert planet. 6 hours later they are dying of dehydration and exhaustion. 6 hours? (Reminds me of the South Park episode where they all go cannibal after only 1 hour without food and eat someone who wonder if they are diabetic.)
Good drama demanded in SG-U, they start suffering on the desert planet soon, within hours, not days later as might be more realistic.
So when creating travel rules, and weather systems, for the Adventure Guide, I know some would feel that the chance of a tornado or blizzard can't be for example, 01 on d%. Since that would mean there is a tornado every 100 days and that is not realistic.
Or Cook expert: sailing rules 2d6 on a 12: Gale, 80% chance of galley sinking. That's 2.2% chance of gale and sinking every journey: the Roman navy would be sunk in a year!
If your players head out into a heavy storm what's their chance of being struck by lightning?
Real 1: 250000
Or are you going to just say double 1 on 2d6?
It is my belief that I am playing a game not a simulation. One still needs laws and rules in a game, that allows player choice and the player's ability to weigh risk, but if my odds of encountering adventure are as close to my normal life chances of encountering some adventure, I don't see myself or my players being very entertained.
In my world, ships sink, frequently and lightning strikes twice, often.
Question 3: What about in your world, what about the the Old School Adventure Guide?