The Ender pouch functions as a portable link to your Ender chest. So you no longer need to carry an Ender chest with you. You will also not need to place anything as the pouch works like a second inventory just a right-click away.
The Ender Tome acts as a portal to your home base. You’ll need to obviously first set your home location with a bed. Then so long as you have the Tome with you, you’ll have a quick link back home. The book, however, is consumed in the process so it may best be reserved for emergency situations. It would make a great asset to hardcore gameplaying as you’ll have to limit how often you use a Tome.
It does have some negative effects, though, so be sure you have some food to replenish yourself on return.