Yes, I do have experience with paid subscriptions. I don’t work for twitter so I can’t answer questions about refunds etc. But being a user, I can share my experience with the API.
Yes, the Premium API is paid, but it does have a sandbox version which you can use before committing to a paid account as Hamza explained, however there are differences between between the sandbox version and the paid version, including search operators, you can find the differences here:
As for your second question, the geo info based on tweets has more granularity (lat/long) but from our experience only a small fraction of tweets has that. Profile geo on the other hand resolves to a lot more data, but profile geo data is based on what the user enters in their profile, so if the user doesn’t enter profile info you won’t get any data (otherwise it would be violation of privacy). The API is not meant to give you any private data, so if you can’t see the information yourself with what’s publicly available then you are not likely to get that information with the API.
Hope this helps.