Hey. I'll start with the second question because it's much shorter: the answer is no. Well, technically when the game dies your character goes with it, but it's a truly ultimate limit.
You can unsub for months and your characters will stay intact.
Now on to the first question, yes, there have been many changes and more are coming. We got Craglorn, a new zone for veteran players. Three trials for 12 people with leaderboards and weekly rewards. Dragonstar Arena (hard PvE for 4 people). New veteran dungeons. Armor dyes, guild heraldry, guild traders. Dungeon scaling, daily quests (crafting, dungeons). They improved delves (those small dungeons with torch icon) - most of them are now larger than they used to be. They're also completely overhauling veteran ranks, we're halfway through and the next update will bring the main phase of it (http://forums.elderscrollsonline.com/discussion/comment/1334674/#Comment_1334674). And they continuously tweaked skills - stamina builds are actually viable now.
As for the future, the justice system will be coming soon, then Thieves Guild and Dark Brotherhood (they're probably a long way off still, though). The Imperial City, mixed PvP/PvE. New zones: Murkmire (aimed at groups, like Craglorn) and Wrothgar (solo).