What comes with Business Plan besides being able to create a monthly budget? Does it allow for more workspaces and bots inside those workspaces? How many bots can you create with business plan?

Yes, unlimited workspaces, 10 bots per workspace

And let’s say I purchased $50 of messages and only used $20, would the rest of the $30 go to my the months balance or not?

It is pay as you go, which means we charge per message, not based on a bundle.