не+adjectives

I always thought that "много" and "немало" are synonymous with one-another. Until this remark by Борис Берман shook that assumption:
"Просто в последнее время появилось не скажу, что много, но все-таки немало молодых «деятелей культуры», которые представляют интерес."
Apparently, they're different. So I guess one could sort these adjectives in descending order like this: много > немало > немного > мало.
Is that correct? And does the same thing hold for other pairs of adjectives like высокий-низкий, etc?
In the case of много and мало, does it make a difference if the corresponding nouns are countable or uncountable?
Thanks in advance.

мало = the quantity is small
немало = the quantity is NOT small

много = the quantity is big
немного = the quantity is NOT big

Of course it's clear that
"мало" < "много"

Moreover we can state that:
"мало" < "немало"
"немного" < "много"

BUT "немного" has no any definite relationship with "мало".
There can be any relationships depending on the situation:
"немного" > "мало"
"немного" = "мало"
"немного" < "мало"

And so is for the "немало"-"много" pair.

For me (a native Russian speaker) "мало" < "немного" << "немало" < "много". The former two are used for small quantities (like "few"), the latter two--for large (like "many", "much"). This is my humble attempt to verbalize the difference: When both "мало" and "немного" are possible, the first one says that the quantity is small and is not enough for something, and the second one that it's enough, although not large. Everything that applies to "мало", "немного" pair also applies to "много", "немало", and vice versa.

"Осталось [ещё] немного бензина." The fuel is low, but there is some fuel yet. Probably it would be enough for something.
"Осталось мало бензина." There is little fuel. Probably not enough.
You cannot say "ещё мало бензина" here, so at least "мало" is certainly not a full synonym of "немного".

When only one of them is possible, for example, because of style, they're synonyms.
"A: Разве 100 рублей за проезд в автобусе -- много? B: Да немало!" -- expressive style, sarcasm.
"Немало воинов полегло на поле брани." -- high style.
In these examples "много" cannot be used, as it's inappropriate for the intended style. But in both cases it means the same as "много" in the neutral style.

Countability doesn't make any difference, I think: мало молока, немного молока, мало студетнов, немного студентов -- all four combinations are possible and different (for me).

I've also asked my wife (also a native Russian), which is more (if any), "мало" or "немного", and she answered that there's some vague feeling that "немного" is more when they both can be used (in fact I've borrowed this idea from her). The author of the sentence cited in the first message also clearly makes distinction between these two words.

(Corrections are appreciated.)

PS: I've thought a little more about this, and now I think that 1. "(ещё|всё-таки) немного" and just "немного" may be different, and 2. the meaning of "немного" may depend on the position of logical stress. But I don't have time now to think more.

Thanks!I couldn't find these things in any dictionary. :)

Оч. интересно! Кстати, помню, я раньше как-то слышал дискуссию о парах слов типа маленький-небольшой, мелький-неглубокий и т .д. Надо сказать, я не очень хорошо вспоминаю все сказанное, но по-моему было приблизительно так:

Принципиальная разница между скажем чем-то маленьким (или мелким etc.) и чем-то небольшой заключается в том, как соотносятся их размеры с размером человека. Так что, например, маленькая стена - это стена, которая не составляет препятствия для здорового человека, тогда как небольшая стена - большая чем маленкой, а все-таки меньшая чем большинство подобных ей стен в подобных местах.
Это правда?