RandomPerson3465 stopped working on new Livecountsedit (v5) as of September 2021. The source code for Livecountsedit v5 (incomplete) can be downloaded here. Livecountsedit is still maintained at livecountsedit.github.io by Sync and Straight from MG.
Yes, but Livecountsedit might not be optimized for mobile devices.
On versions before v4, and the old compare mode, all the options should be on the top left of the screen. On regular mode v4, click or tap the "Options" text at the bottom left corner of the screen, and on the new compare mode there should be a gear icon on the top left.
You are not required to give credit whenever you use Livecountsedit in your content.