Whether a Windows operating system is characterized as 32-bit or 64-bit has no bearing at all on data. As long as you have application programs that can "understand" the data files, you're good to go.
For example, if you have *.doc or *.docx files that you created using Microsoft Word on your Windows 7 32-bit system, you will be able to read and edit those files once you install Microsoft Word on a Windows 10 64-bit system.
That would be the case even if you chose to install the 64-bit version of Word on the Windows 10 system -- but you probably do not want to do that. Microsoft Office defaults to installing the 32-bit versions of its applications even on systems that are
running the 64-bit version of Windows. See
https://support.office.com/en-us/article/Choose-between-the-64-bit-or-32-bit-version-of-Office-2dee7807-8f95-4d0c-b5fe-6c6f49b8d261
If you had just copied files from your current computer to your external drive, you could just copy them back from the external drive to your new Windows 10 computer.
If you used the "Backup and Restore" routine built into Windows 7 to create your backup, this article explains how to recover your data:
https://www.pcworld.com/article/3034527/windows/restore-a-windows-7-backup-in-windows-10.html
If you used some other application to create your backup, you may need to install that application on your Windows 10 system to recover the data.
I am under the assumption that The only difference between a 32bit and 64bit O/S is the amount of Data transfer is increased and the system runs faster.
Not quite. As far as most home users are concerned, the main difference between a 32-bit version of Windows and a 64-bit version of Windows is the latter's ability to use more RAM. The system may or may not "run faster" if it has more RAM; that depends on
what you're doing. And, of course, there won't be any change at all unless you actually install more RAM (assuming that your hardware permits that).
I also understand that EULA has a thing were if you make changes such as your mother board or other components you will not be able to activate your operating system. You will have to call Microsoft to activate your O/S.
If Windows came pre-installed when you bought your computer, you have what's known as an "OEM" license. This license is limited to the computer on which Windows was first installed. That means that you can't use the same product key to activate an installation
of Windows on a "new computer."
Windows monitors changes in your system hardware, and Microsoft has a secret algorithm that "decides" that you have a "new computer" if too many hardware changes are made. Outside of Microsoft, no one really knows how many changes are "too many," but it
is generally accepted that changing the motherboard will definitely trigger this detection and result in your installation of Windows being flagged as "unauthorized." There is an exception if you replace a defective motherboard with an identical model (or
one that the manufacturer offers as a replacement if the original is no longer available). If this happens, you will need to "re-activate" Windows by telephone.