Will my email keep working when I connect the domain?

If this domain has no email set up (most fresh .ge domains don't), changing the nameservers can't break anything. If the domain already has email (e.g. info@yourshop.ge), switching to nameservers would stop it — in that case use the "Advanced" option on the screen: instead of nameservers you add two records (A/CNAME) and your email stays exactly as it is. The Sellit screen warns you automatically if it detects email on the domain.