You would be fine to go ahead and install now. The trial licenses are all for 30 days. Once you have the license you would go to the "All Settings" page in Orion and at the bottom you will see license manager where you can easily update your license with the key once you have it. Hope this helps!
Loop1 Systems: SolarWinds Training and Professional Services
I forgot to answer the final question. There are no limitations during the trial period.