Have a look at https://github.com/NamelessMC/Nameless/wiki/Setting-up-SMTP-with-Nameless-(e.g.-Gmail-or-Outlook) for information on setting up emails.
The info there works for both v1 and v2, apart from the email settings which are viewable in the StaffCP -> Configuration -> Email tab in v2.
If you need further assistance with this, you can join our Discord (link is on the homepage)
Use the v2 plugin: https://www.spigotmc.org/resources/nameless-plugin-for-v2.59032/
I'd also recommend that you generate a new API key; it shouldn't be shared with others. You can do this in the StaffCP -> Configuration -> API tab.
So Xemah's Discord count is something completely custom, using the Discord API, and unfortunately I don't have any code available to send to you.
You can add something like this to your template to display a shorter version of the server status, and edit the text in the file custom/languages/language/general.php to get rid of the "There are currently" part of the text.
I can't send any CSS for this since Xemah made it himself, and as it's a premium template it can't be shared.
What exactly do you want to change it to?
Should be last_seen_x in custom/languages/language/user.php