Learn English – A few were, or a few was

The key is that you have men and frogs- both plural. Saying a few men is no different than saying some small number of men- which is clearly plural.

So the correct sentences are: A few men lift the table. And A few frogs jump out of the lake.

BUT, your second sentences are also grammatical- they just mean something else.

For example: Many men have tried, but few men lift the table.

Few frogs jump out of the lake- they seem to prefer to remain in it.

You should use prices because the following verb you used is plural - were. This means you are using two prices - the price of hardware and building material and the price of IT products.

"As the selling prices of hardware, building materials as well as IT products were under downward pressure due to stiff competition, the company's business environment is expected to be remain challenging in the coming few quarters."

Note that you can use plural prices for single entity there because that entity itself contains products. For instance, The prices of IT products --considering several products' prices.

The word price is countable and uncountable both.

You may consider a better version of the sentence as suggested by Jay and Damkerng: As the selling prices of hardware and building materials, as well as IT products, were under downward...