UPDATE May 2016: Minimum requirement for applications is a level 260+ PvP viable character. Guild slots are very limited in ToS compared to traditional MMOs and due to guilds requiring a leveled Templar to create, there is no plan to create more than 1 guild tentatively. Slots will be very competitive, inclusive of a Trial for new recruits and subject to ToS Guild Chapter leadership's discretion on who get to keep the slots.
Some members have been enjoying a bit of GvG action in ToS. Enjoy this video made by Batcat: