#1: Your PBAOE mez only gets worse with level. The mez is supposed to be less effective on higher level mobs, but the way it was implemented on P99 is that the song gets less effective the higher level the bard caster, not the NPC recipient. I don't agree with this implementation, but do not have any evidence to the contrary. This was done to combat zone-wide mezzing in Fear and more-so KC. Yes, songs (and spells) can be interrupted without actually stunning the player, this is classic. Its the same way PC 'kicks' suddenly start interrupting at L55.
#2: You get a super-human feel for it. I typically get 5 songs in between charms. So where my normal twist is four songs, I charm (song #1), sing 4 more songs, and then recharm. The mob is usually uncharmed for <1 second. This is different than non-mezzing/charming twists, where I just do 4 songs total + click BoH. As for mana intensity of charm, you are still fucked after FT. Classically, FT does not function on bards (
http://www.afterlifeguild.org/Thott/retune.php), neither does mana song, clarity, nor medding.
#3: Just learn the quirks. Guardian rhythms stacks with the other resist rhythms, but the AC component of guardian prevents it from stacking with the AC component of Chant of Battle and others. The issue is bard buffs (and debuffs) typically have multiple functions, if one of those functions conflicts, the rest of the buff doesn't work. As an example, we're currently in an era where root and snare do not stack, which sucks for bards whose slow is tied to snare and cannot slow/snare when someone's rooted the mob.
#4: I typically use weapons in a group unless I'm the only melee, then I'll ask the group to root and I'll DoT. I haven't done true parses, but I just feel my melee DPS is about on par with DoT DPS (for solo targets), but if I can't put up full DoTs because I am hasting other groupmembers, I might as well not DoT at all and just melee while buffing the melees.
#5: I do not typically dispel. I feel I don't have the spell slots, but I might reconfigure. (I typically use snare or mez to pull so my two or three pull comes staggered into camp instead of all at once).
#6: Fearing in dungeons is dangerous. You could also chain mez shaman, but then you aren't getting your other songs in.
#7: Click on it with your mouse. Get used to camera angles that maximize your clickability of the camp/kill-zone, even if they make moving slightly more annoying.
#8: I do not announce what I've mezzed/charmed with a macro. I usually pull 2, charm the second that gets to camp and let the tank kill the first. If I pulled 3+, I just manage it quietly. I'm already pressing songs and click-targeting, I don't have time to spam mez messages on songs that fade every 12-18seconds, plus its annoying.