Welcome to Linux. 
The first thing you need to know is that choosing EndeavourOS as your first distro means you might have to make your hands dirty for a bit - it’s rolling and some things might break on the road. But generally, most things, when they break, are easily fixable and if not, remember to make regular backups - not only of your personal data, but also system files.
This being said, you might want to install Timeshift since it’s arguably the best application to make system snapshots.
For easy steps on how to maintain EOS and Arch, there’s been several great tutorials which were helpful for me when I started my EOS adventure a couple of months ago:
And as for replacements for popular Windows apps - I hope no-one will @ me for that, but folks from Linux Lite created a nice list. Just bear in mind that some of them are desktop-specific tools, so it might be a good idea to do a more detailed research:
My other thought is not to be afraid of terminal. Terminal is your friend, even if there goes some confusion about what to type - just read the documentation or consult the forum.
Have fun!