Hi. I understand that you would expect something from an addon but the description states clearly that the addon is not intended for Auto-Saving of session. At the same time popup size is simply limited by Firefox, that's the maximum any developer can do, simply I can't make it bigger than that because that's and API limitation (nobody knows why just Firefox stupid decisions).
Regarding the full-page or new-tab -> those options are already available
Regarding search in tabs: yeah.. sorry that's a feature that would've been nice but was not able to implement it.
Auto-Save: There is some autosave implemented but not a full-featured like maybe other addons might have, but the whole purpose of the addon is to manually save what you need.