The solution can scale. 

Depending on your plan and the cost, it expands. That said, for the web server testing, there's a limit to the number of users you could add. For the API, you can do hundreds. However, for the web surfer test, it is limited to 100 or 250. I'm not sure yet.

Only our team is using the solution right now. There are two of us doing testing with it.  

Not at all.

No issues.