Can you write off HELOC payments

Can you pay the minimum amount (just interest) and write it off at the end of the year?

Does the interest rate on a HELOC fluctuate? Or can you lock on in?

How long can you take to pay it back? I know it varies but is it around 10 or 30 years.

HELOC interest is generally deductible. there are a few exceptions, but if you have to ask the question, they probably don’t apply to you.