Adding Users with Adobe Sign for Small Business & Additional Transactions

There are two questions that I've been trying to get answered for weeks and can't seem to get any help. I'm hoping that this community support is more fruitful than the other avenues I've tried! 

1. I have Adobe Sign for Small Business which, from my understanding, allows for 150 transactions per year. I work at a yoga studio where we're using this to send contracts individually to people joining our teacher training programs, our instructors, and our guest presenters. On average, we have around 220 contracts that need to be signed per year. Is there a way to add more transactions to the Adobe Sign for Small Business account? Do we need to upgrade? What would the next pricing option be? 

2. It's my understanding that Adobe Sign for Small Business allows for 1-9 users. Can these users create and send documents for signature? Do they have a separate login from me (the administrator)? How can I set this up?

Thank you for any/all help