Hi,
> it was installed under the WAMP folder - on the new Win10 machine it appears to have installed
> under a WAMP64 folder
This means that under Windows 7 you have Wampserver 32 bit and under Windows 10, Wampserver 64 bit.
Copying the folders of your local sites (wamp/www/myfolders/) from W7 to W10 will not cause problems.
For databases, I'm sorry, but the only solution is export/import in SQL files.
One could have tried to copy MySQL data folders, provided that it is exactly the same MySQL versions on both sides (W7 and W10), but since it is 32-bit versions on one side and 64-bit versions on the other, it has almost no chance to succeed.
As for PhpMyAdmin read Right-Click -> Help -> PhpMyAdmin Help
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Documentation Apache -
Documentation PHP -
Documentation MySQL -
Wampserver install files & addons