How many portals did Ner'zul open?

[Rebirth]

When he was trying to escape? And how many did his deathknights his his orcs get through?

And furhtermore, is this a universe with unlimited planets, that hte Legion and the Titans destory and reorder respectively? Will this battle between the races of Azeroth, who seems to be the only ones capable of combating the Legion successfully, extend beyond Outland and Azeroth?

[Timolas]

All I can say is; possibly ;)
As for the number question, Ner'zhul didn't take that many of his followers through.

[KardenTheHunter]

Actually Rebirth, the answer your looking for is yes. In the WoW Expansion, The Burning Crusade, later down the line Blizzard will release in different patches 7 different portals to limited Worlds where Azerothians can fight the Burning Legion on tainted worlds. Whether or not Blizzard will actually implement these new portals and planets remains to be seen. I've a feeling they may back out but we'll see.

[Kenzuki]

Actually Rebirth, the answer your looking for is yes. In the WoW Expansion, The Burning Crusade, later down the line Blizzard will release in different patches 7 different portals to limited Worlds where Azerothians can fight the Burning Legion on tainted worlds. Whether or not Blizzard will actually implement these new portals and planets remains to be seen. I've a feeling they may back out but we'll see.

They will have to reopen these portals, as Illidan closed them.

[Rebirth]

is there ay lore/info on these other planets? any of the old Horde get through?

[Kakwakas]

is there ay lore/info on these other planets? any of the old Horde get through?

Well, the one Ner'zhul and those under his rule jumped into just led straight to the Twisting Nether and they got screwed by the Burning Legion.
The Alliance forces that were on Draenor, however, jumped into a portal and are still alive, assumably back on Draenor.