The Crossbow of Accuracy has +5 THAC0? Hot Damn! Too bad it's got a slow shooting rate....maybe a cood tactic would be to use the Crossbow of Speed against roadkill and average enemies, then whip out the Heavy for the tough dudes. But I still don't like crossbows in general. The only specialty arrows I like are Piercing and Detonation, neither of which come in Bolt form (I'm pretty sure.) Bolts of Lightning are okay, I guess, but Polymorphing (can you buy those at Sundries?) just aren't worth carrying around, as anyone tough enough to use them on is just going to Save vs. Spell anyway.
I've got 4 archers in my party, and there are 4 great bows (Longbow of Marksmanship, Composite Long+1, Long+1, Eagle Bow) in the game, so they all kick ass with plain ol' normal arrows.
As for Bardhood in general, 80 HP is certainly good, but think what you'd have if you'd built a Fighter/Thief instead. Sure, you can't cast any spells that way, but Imoen's already the best mage in the the game. The party I'm playing now has me (Tank Fighter, dual to Thief at Lev. 7), Imoen, Canderous, Kivan, Minsc, and Coran. I do Traps, Imoen does Pockets, Coran does Locks, and we ALL do Stealth, and we've each got 100% or more in what we've studied. As for your Bard casting 4th Level Spells, Imoen can do that from Stealth, and with the Eagle Bow, Gauntlets of Weapon Skill and 19 DEX, she's equal to the Light Crossbow of Speed any day.
Sorry to bag on Bards like this. I thought carefully about building a great Bard (God knows the NPC ones suck big-time), and decided they are indeed good, but they've got too many weak points. Sure, they've got great Lore, but when designers give such a paltry ability to a class, it tends to be because they're trying to make up for that class's weaknesses.
Having Lore over 100% is indeed amazing, but I think you don't need to go any higher than 80 or so. For fun, I once hacked a guy to have 25s in everything, just to see what he could do. His Lore at Level 1 was 84: This guy could ID the Tomes! I think the only things that WON'T ID, no matter your Lore, is the Cursed stuff. Besides, if you've been through the game once or twice, you already know what and where everything is.