Can guildmembers bind in the guildhouse and /release to it after they die?

Yes. If the guildmembers have permission to use the bind stone, they can bind anywhere in the house. Typing /release house will teleport the guildmember to the guildhouse. Typing /release will bring him/her to their last normal bind spot. /release house will always return the player to the last house in which they bound themselves.