We are currently investigating issues some players are having on the megaservers. We will update as new information becomes available.
We are currently investigating issues some players are having with the ESO Store and Account System. We will update as new information becomes available.
Your question is pretty broad however, use them offensively to set up a full burst combo and confirm a kill, or use them to escape in a sticky situation. They pair well with cast time abilities, for example dark exchange on sorcerer.
Elswyer did introduce some new alchemy ingredients but I don't think any of them works with immovable. I still use the mag+health+immovable pots. Detect+mag+immovable if I come across a cloak spammer.