Returning player (kinda).
1) You won’t get anything extra as a result of them introducing free accounts. But you also don’t get any of the restrictions which are on free accounts. For example they only have 2 character slots, only 3 bag slots, can’t use map chat and can’t buy or sell most items on the trading post.
There’s a full list here if you’re curious: https://help.guildwars2.com/entries/95982157-Account-types-Free-Core-HoT
2) A lot of the changes from HoT won’t affect you unless you buy the expansion. But depending on when you stopped playing you may find a lot has changed as a result of updates. It’s hard to list (or even remember) but there’s a short summary of the major releases here: https://wiki.guildwars2.com/wiki/Release
3) See 2.
4) It depends on when in 2014 you stopped. There was a whole storyline (Living Story Season 2) released during that year, which included 2 new maps (Dry Top and Silverwastes).
“Life’s a journey, not a destination.”