Pants are always plural ? Yes, trousers, scissors, glasses In modern language, yes. your pants / jeans are cooler than Kanye West’s cooler - requires the comparative form.

Yes, always...

If you say pants, scissors, shorts, etc the plural form of the verb is used but if you say a pair of pants or a pair of scissors, the singular form can be be used. “There is a pair of scissors on the table.”

Yes

Also, underwear are plural as well. "These are expensive underwear."