Thanks for the review. Regarding quick-start guide, I sort of have something in the form of those tutorial images that present all the main features of the addon (the Tutorial was suppose to be automatically opened after you installed the addon but you can always re-open it from the top-right addon menu button -> About)
Regarding opening of multiple session at once, sadly this is not possible right now but I do have plans to support with a future update. Sorry for not providing this feature yet.
(For more info regarding feature updates you can visit https://github.com/ReDEnergy/SessionSync/issues/40)