my home folder is infested with /.folder and /.temp

Solution 1:

These files are normal to see in a Linux environment if you aren't hiding hidden files. They are created by various programs to store data in your user profile.

They are TYPICALLY hidden - in Linux, prefixing a directory or file with a . marks it to be hidden. Hit Ctrl+H to see if that hides the items from view. There should also be an option from the hamburger menu (the button with three horizonal lines in a 'hamburger' like pattern) that says "Show Hidden Files" - and you should uncheck that to hide those dot-files as they are typically called.

Deleting them will remove your settings and files, which will cause problems if you intend to use your applications. such as Thunderbird and keep your mail. DO NOT delete the files and folders.