Has any issue ever specified how many pounds of web does he wear or how much a cartridge can contain ?

As much as the plot demands.

Well said.

Well I asked this question because when we see him shooting his web, its shape is huge compared to the cartridge and I wonder, how much does it weigh ? Can it be cumbersome to lift that much and swing with it all the time ?

this is true. however I think I read somewhere that each web cartridge held several hundred meters worth of liquefied webbing

It's stated that the web formula expands upon contact with air. Even if it would be cumbersome for a normal person to carry around, Peter can press up to 10 tons before seriously straining himself, so he should be fine.

A huge amount.

Peter Parker at this point has the brains (and money) to invent unlimited webbing via parker particles and using a sort of mechanism to create the paricles out of spinners and comicbook science quantum mechanics.

That would be cool.