I have to disagree with most of the things you listed.
First of all, I almost exclusively play gray elves.
This means of course I'm well aware of how toughness and strength impact the gameplay difficulty for the race.
However, my feeling is that the current situation is well balanced.
Elves have always had a tradeoff where they excelled in attributes related to magic or archery and much less so in areas related to melee and general combat endurance.
I do find potions of attribute potentials around and I frequently get my toughness and strength to 20 or more by the time I hit level 15. I'm talking about characters that start with ~9(12) in strength and toughness.
Moreover, I think the incentive to visit the random caves that you mentioned, is already there - the very potions of potentials mentioned can drop randomly from monsters there, including the vaults.
That, plus a bunch of other items one can obtain by clearing various levels of all the random caves make visiting them virtually mandatory.

Right now you need to be careful in the early crucial phase of playing a physically weak character.
It forces you to learn to avoid some monsters and some areas, requires frequent switching of tactics and gear and teaches you to run when things get hot.
I would not trade these qualities for easier potentials because that would only serve to cheapen the experience.

Current situation also forces you to be smarter in how you use the potions of attribute and attribute potentials.
Before this, you could just drink them all and move on. Now you are forced to employ some planning where you increase the potential with any of the randomly found potions and then train the attribute those 2 points, possibly with herbs or running around very strained.
After that you might drink a blessed poga or potions that directly increase a single attribute. Wishing for potions of potentials becomes an attractive prospect.

The principle of playing low toughness and low strength characters pretty much boils down to having PV.
With elves it's additionally important because they can utilize their high Dx to also increase DV and gain greater range of useful tactical settings.
Tactics... it has a huge impact on survivability, especially when you can't rely on toughness and HP.

Elves require a lot of flexibility from the player but also reward them once you reach a certain threshold.
I wouldn't want to have the potentials more easily increased because I have learned to work with strength and toughness around 10-12 at the point in the game where DV/PV isn't so significant.
What you are suggesting with the Ice Queen or random dungeons is a mid-game feature (levels 15-20) at the point when strength and toughness aren't that important anymore:
- you have items of carrying or SoA to improve the otherwise lacking carrying capacity;
- you have PV in excess of 20 and HP around 100 which allow you to survive pretty much anything (random monsters, not uniques).

At this point improving toughness and strength potentials isn't really high on the priority list.
I think that the state of things right now forces you to employ different strategies when playing different races, much more than it did in the past. That is a good thing.
You just need to find out how to properly play elven characters and use the advantages they offer to increase chances of survival, instead of changing the gameworld to accommodate a single, uniform playstyle for all races.

I'd say "Yes for Strength, No for everything else".
Very Low Strength characters are unplayable unless you luck into Strength of Atlas book.
Or just modify starting Strength Potentials for everyone so that you can lug around ~2000 stones of gear.

Increase the carrying capacity given per point of str. That way you don't have to worry about giving weak pcs other advantages of increased str (like higher melee damage).

Actually 2000 stones is 100kg if I'm not mistaken... I'm not able to carry so much right now :). Why level 1, say, hurtling should be able to carry so much?

So handing the player a means to compensate for one racial deficit -> making all playstyles uniform? I think this is what they call hyperbole.

The low toughness score presents a problem because certain enemies (namely, chaos wyrm) can insta-kill you if your toughness score is too low. What you call "Properly playing" consists of two things:
1. take a gamble.
2. grind until you acquire enough random stat potions or enough levels to raise your hp into an acceptable range for survivability.

Yay, fun.

The game is all about preparation. The only question is how. When the only source of preparation is random, you either let randomness test your patience or you go in knowingly unprepared. I think there is a fine line between this being enjoyable and annoying.

I am unopposed to giving people more outlets of control over their characters weaknesses--for a price. I don't particularly think the OP's specific suggestions are the best ones but the idea behind them I agree with.

I think if one gets one of these compensations, they should have to forego something else. Example: thrundarr drops a pile of potential toughness potions instead of big punch if your toughness is below a certain amount--much like he gives potion of lit if your literacy is inadequate instead of an inventory id. Not both.

Well, I like food, but I would probably be hurthling monk by Ancardia standards. Even with moderate needs of let say 3 large rations a day, that is 600 stones of food which is arround 30 kilos...

I think fixing St problems would be better via scaling carrying capacity at least linearly.

Currently moving from St 5 to 6 adds 40 stones which is bow and 10 arrows or less than metal cap.
Moving from 25 to 26 gives 300 stones increase....
If one looks as percentage increases in first case ~20% of St was added, while in second only 4%. Personally for me it never made any sense.

There's a big difference between "being able to carry that much" and "having potential to train to eventually carry that much".
And I doubt you wouldn't be able to move even 1 step with a properly distributed load of 100kg - every soldier is expected to march 25 km per day with a load of 50kg, on a regular basis - so twice that is nothing sensational. In the worst case you can make some kind of sled to pull...
2000 stones in the game is the minimum weight of a decent set of equipment - a couple blankets, 1-2 rations, some herbs, keys, climbing set, body armor, helmet, girdle, gauntlet, boots, weapon, shield, bow, crossbow, pickaxe, ~50 arrows, ~50 crossbow bolts, a dozen rings, a dozen potions, a dozen scrolls, a dozen wands, a few thousand gold...