mehra03
Alright, the Swiss Travel Pass (with Flex and Youth variants) is a product endorsed by the Switzerland Tourism association myswitzerland.com and just happens to be also sold by SBB (but also world-wide from tourism offices)
As the STP is only available for persons residing outside of Switzerland, you won’t find a lot of first-hand experience with it in this Community, which mainly consists local Swiss residents.
Myswitzerland.com do offer STP Help / FAQ pages here and here, which should cover most if not all of your questions. If not, on the second one you’ll find a chat feature at the bottom of the page (= different community from this one, probably myswitzerland.com sales staff)