Sweeping Strikes > Whirlwind does generate some great initial threat on an AoE pull.
Yeah, if they have Improved Battle Shout and you don’t, then that’s a tradeoff. Typically in 5 man instances, if you’re tanking as a warrior, you’ll want to be the one applying Battle Shout.
Elite’s Warrior Tanking Guide has some pretty useful macros and general advice for warriors getting started with tanking Classic instances.