Hello Paul,
1. The only 2 ways that I know of getting MP3 files available for people to listen to on this forum are how I have done above, by dragging the file into the "drag files here section" or by putting them in Soundcloud and copying the link in the browser of the page containing the song that you want to share.
For anyone who does not know about Soundcloud it is free to join and you get a limited amount of space to load and keep your songs.The limited amount of space in Soundcloud (for free) is the reason that I have started embedding MP3 files into the forum using the first method.
2. I do not have any experience with Studio One but I did a quick search on the internet and I found this answer to the file formats question:
"I think you need to convert your files to one of those audio formats I think. They are mp3, ACC or WMA. You can try Mediabuddy tool for it."
I personally use this online media converter as it was recommended to me by BobF_ on the L&M forum http://media.io
I am glad that you are getting in to home recording Paul, please reach out to us if you need any help. Perhaps some of the folks reading this will be able to supply you with better answers than I can.