I currently have Windows Live Mail under Win 7 Ultimate. I would like to do two things, if possible:

(1) Back up, and be able to recover, either into Win 7 or Win 10 (whatever is the recommended e-mail client for Win 10), everything: folders; saved e-mails and all of their attachments (if any), in the folder(s) to which they have been saved; contacts (address book); all categories and the entries (contacts) therein.

(2) Migrate all of the above to another e-mail client, preferaby cloud-based and Web-based, such as Gmail. 

I have looked at many dozens of articles and tried a few methods but all were unsatisfactory including the "Export" and "Import" that is supposed to be a function of Windoes Live Mail. I need a solution, as I have a lot of saved e-mails, some of which are business-related. Any help will be hugely appreciated! Thanks in advance. *** Email address is removed for privacy ***