جتنی چادر دیکھئے اتنے پاؤں پھیلائیے

Primarily yes, but it can be used for any resource like time or energy.

Yes, if you are discussing a project budget, it sounds professional and wise.

There isn't a direct proverb, but the concept is 'Fuzool-kharchi' (extravagance).

Because when you sleep, your feet are what stick out of the blanket if it's too short.

'Phailaiye' is formal/polite, 'Phailao' is neutral/informal.

It is traditional, but it's still used daily in news and homes.

Not usually. It's almost exclusively for financial or resource management.

A 'Chadar' is a thin sheet; a 'Kambal' is a thick blanket. The proverb specifically uses 'Chadar'.

Yes, it is exactly the same in Hindi: 'Jitni chadar ho utne pair pasariye'.

You would say: 'Main jitni chadar hai utne paon phailata hoon'.