I wonder, how hard it is for the high level rogue to sneak into the city such as stormwind or Ironforge? Also, is there a way for that rogue to summon his party members waiting outside to his location inside the city??

level 90 rogue should be no more prob sneaking o the city..at least your level please try to be close/similar with pak guard there. the lower ur level, the higher chance pak guard gonna caught you.Use distraction might be helpful. Srry I dont have level 90 rogue. Capping exp at lvl 73:)

No way to summon I guess because HGWT already being remove and need 2 ppl atleast at summoning stone outside The Stockade.