are there any good modpacks that will essentially allow me to group attack with units, better yet, group attack while giving me options on which troops attack first and which don't?

I'm trying to shorten up the lengths of my games [especially in the late-game], and I'm finding the sheer number of units too much to handle. Especially when it comes to air power and having to bomb with units individually.

Try RevolutionsDCM (http://forums.civfanatics.com/showthread.php?t=262937), has everything you need

Standard civ 4 has the ability to attack using an entire stack, just tick the 'stack attack' option in the game settings, with that the AI tends to lead with collateral and flanking units too (you need to shift click (cntrl helps too) your units to create the 'stack' though. If you haven't already the 'quick battles' and fast movement options help speed things up too.