Prepositions before adverbs

Question

I've found quite a few words, expressing quantity, which may be preceded by an accusative preposition and remain the same.

However, I'm not sure if they may be preceded by prepositions requiring different cases.

I'm talking about много, мало, более, сколько, несколько, столько, больше, etc.

As far as I know, in need of declining these adverbs, много and несколько may be replaced by the adjectives многие and несколькие, respectively.

But what about the other adverbs?

If I want to tell "to live with little money", does it make sense to say "жить с мало денег"?

"You can trade more than 60 cryptocurrencies" - "Вы можете торговать более 60 криптовалют"? (I know that торговать normally is followed by instrumental).

Finally, "We got to live with less money" - "Мы стали жить с меньше денег"? "Мы стали жить с деньгами поменьше"?

Answer 1

1. As far as I know, in need of declining these adverbs, много and несколько may be replaced by the adjectives многие and несколькие, respectively.

несколькие is incorrect, its Nominative is still несколько, but it declines in the rest of the cases

If I want to tell "to live with little money", does it make sense to say "жить с мало денег"?

To express such ideas in Russian one needs to get creative by either adding words or replacing them.

жить с малым количеством денег
or better yet
жить с небольшим количеством денег

2. "You can trade more than 60 cryptocurrencies" - "Вы можете торговать более 60 криптовалют"?

Here to более you add чем (just as in English more than) to first get to

Вы можете торговать более, чем 60-ю (шестьюдесятью) криптовалютами

The problem here is that in Russian валюта is a collective class name, whose plural is rarely used in Instrumental. Therefore to sound idiomatic the sentence needs to be modified into

Вы можете торговать более, чем 60-ю видами криптовалют

3. Finally, "We got to live with less money" - "Мы стали жить с меньше денег"? "Мы стали жить с деньгами поменьше"?

Similar to the example for the question #1

Мы стали жить с меньшим количеством денег

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^{So let's try to sum up, for collective or uncountable nouns in cases other than Nominative and Accusative:}

^{много is declined in the form of большOе количество
мало as небольшое количество
более/больше as большEе количество
менее/меньше as меньшее количество
сколько as какое количество
столько as такое количество
несколько as некоторое количество}

^{So basically in contrast with English the role of the main object is assumed by the word количество while the word which was supposed to be the main object is inflected in Genitive answering the question количество/а/у/ом/е чего? - of money, of problems, of days etc. And if a collective noun clearly represents volume количество can be substituted with объём}