Edits to core files can be lost if the patch includes those files. For templates, always edit outside of the base template to avoid this. Changes to settings, page builders, etc. - anything through the admin panel is normally preserved.
As always, you should make a backup before applying any updates. As for 7.2, an update for 7.1 will be released later, either in another beta or with the stable release.
As always, you should make a backup before applying any updates. As for 7.2, an update for 7.1 will be released later, either in another beta or with the stable release.