What order should I do these steps in?
Legal structure and your EIN come first, since you'll need them to open a business bank account. After that, banking and bookkeeping setup should happen before you take your first payment.
Do I really need a separate business bank account?
Yes, strongly recommended even for sole proprietors — it makes bookkeeping dramatically simpler and is required to maintain liability protection if you're an LLC or corporation.
How much should I set aside for taxes?
25-30% of every payment is a safe starting estimate for most small businesses, though your actual rate depends on your income level, structure, and state. A tax professional can give you a more precise number.
Is this checklist different if I'm in Canada?
Yes — see the Canada version of this checklist, which covers CRA registration, GST/HST thresholds, and Business Number requirements instead.