Will I be able to freely walk around and bask in the nostalgia of my childhood days without fear of other players killing me?

Personally I'm not a big fan of PvP, but I do know it's a very large and crucial part of MMORPG's

Will I be able to turn off PvP and roam Cyrodill in all it's glory?

it is forced, it is the only PVP zone in the game.

So I'm unable to turn it off and roam the biggest area in the whole game?

All PvP that I engage in is non-consensual. You shouldn't have been dressed like that if you didn't want it.

Honestly I hope so. It's a war after all.

Plus there's no different PvE or PvP servers. And I remain first and foremost a PvP fan, if other MMOs are anything to go by.

you can roam it all you want, just watch your back.

I see raids of ppl running arround to just farm legendary resources^^...nice xD!

Nope. Its not forced at all.

If you're adventuring in Cyrodiil and run into an enemy player, of course you have the option to fight (ie. engage in PvP.) On the other hand you could run away or let the player kill you, thus avoiding PvP all together (since you won't be versus anyone.)

I'd recommend making good use of the stealth system and running away from players when you see them if you don't want to fight. Though I personally don't get why its different than fighting the mobs, only better.

Some people might ignore you, I'd guess most would just try to kill you.

Fixed it for you.

How will player/ player stealth work? invisibility?

Apparently all classes can stealth and only thing that makes the difference is the distance at which players can see you in stealth. A light armored character with skill points in stealth will be detectable at a much shorter range than a warrior in heavy armor. Or I could be wrong.

You should be able to explore Cyrodiil somewhat safely within your own territory, and slightly less safely in enemy territory. If you sneak around and stay away from the big battles you shouldn't run into too many people.