Nah got the info from the Activision destinythegame.com website.
It says it all right on the site.
Following years of strife, what remains of the Reef has fallen to lawlessness. You and Cayde-6 are sent to personally investigate the recent unrest. Upon arrival, you soon discover the most-wanted criminals in the Prison of Elders have organized an escape. Beyond the Vanguard’s authority, you’ll pursue these fugitives deep into the Reef. Explore new regions, awaken new powers, earn powerful weapons, and uncover long lost Awoken secrets. The hunt is on.
Alongside seasonal updates and live events available to every Destiny 2 player, Forsaken Annual Pass provides bonus rewards and introduces three premium content releases (anticipated in Winter 2018, Spring 2019, and Summer 2019).
Annual pass comes with:Each release delivers new experiences to Destiny 2: Forsaken, including activities, end game content, and an arsenal of powerful weapons, armor, and gear to earn.
Check out destinythegame.com/forsaken and just read. It's all on there.
From destinythegame.com:
>"Alongside seasonal updates and live events available to every Destiny 2 player, Forsaken Annual Pass provides bonus rewards and introduces three premium content releases.
>
>Each release delivers new experiences to Destiny 2: Forsaken, including activities, end game content, and an arsenal of powerful weapons, armor, and gear to earn."
FYI, I went to:
https://destinythegame.com/buy
And clicked on the Forsaken link for the various platforms. Xbox and Steam takes you to a place where you can buy it, but PS4 doesn't. Check back on it periodically and see if Bungie/PSN fixes it.
destinythegame.com/compare should help with the version you want to buy. There isn't much known about the upcoming dlcs which will be in the annual pass. You might want to consider waiting before buying the annual pass but I think it saves you around 5 bucks if you buy it all together.
Leveling up isn't that hard. Playing the campaign and doing some public events should bring you to level 50 fairly quick. The grind starts when you reach the soft cap at light level 500.
There is definitely a version that only contains Forsaken - it's what I purchased.
Another way to find it: go to destinythegame.com, select Preorder, select the edition you want, platform, etc. and select Microsoft store. I did that and found this version which contains just Forsaken and costs $40.
Vanilla is capped at 300 base, 305 with mods. If you don't have CoO you cannot attain 335 max PL. To your point about needing CoO to play, I'm not sure. But you never could play D1 DLC without its previous expansions, so assumption would say that this will be the case for D2.
Edit: After checking the PS Store and destinythegame.com, there is no indication on either site that Curse of Osiris is required for download. I would take this lack of confirmation as a sign that it is not a prerequisite, although, as another user mentioned below, you'll be locked out of DLC 1 content such as strikes/Nightfalls, exotics, raid lair and patrol space.