I think there just has to b atleast 15+ on daily, not 100% Sure
They will be counted as one person ofc and for the requirement you need 15 different people.So they could stay in the guild.It won't be a problem but they will be counted as 1 person.
Oh okay that's good to hear! Does this still apply if they have completely separate accounts for these alts? They're not all on one username/email.I know nothing about this so forgive me if these are stupid questions! Thank you for your patience with me xD!
You're worrying too much. If you're serious about your guild and you know you'll grow it. Just send the logo to aga. straight away. Logo patches don't happen every week, so most likely by the time it does get patched you'll meet the requirements.