yes you can . . .

For SaaS . . . use Stripe.com for payments.

When you start out I wouldn't form a company until you have revenue . . . once you grow your SaaS to a few hundred dollars of recurring revenue it's time to form an LLC. <$500 in most states.

You could form one right away if you feel your SaaS is at risk for a lawsuit or you have a large amount of assets . . . but typically waiting till you have signups and regular revenue is recommended.

Listen to: http://StartupsForTheRestOfUs.com

read/listen to everything by patio11

Good luck in 2015.