There are several reasons for the creation of the account, some are related to the ability to have business model for the Premium version, some are related to offering convenience and security for the users. I’ll be writing a blog post about this soon, stay posted!
Yes, you can right-click and encrypt/decrypt files in Windows Explorer and double-click to decrypt/open/semi-automatically re-encrypt files.
Yes, AxCrypt 2 will upgrade an AxCrypt 1 installation. No need to uninstall first. No harm done either.