Supplier contracts

What is the term of the contract? Ideally nothing more than a year.
What are the termination provisions? Ideally nothing more than a month to terminate.
What are the payment terms? Ideally 60 days from invoice date.
Is the pricing model based on perpetual licenses? If yes:

Are there any ‘gotchas’ with perpetual licensing terms i.e. the licensing expires if support falls away?
Are there any annual prices increases that are built in?
What is the support & maintenance cost?