[Lord]

Items that can be used to cast the music don't have a certain number of charges, although they might be usable just x times per day.
Are you running BGT or BGtutu?
There is most certainly not more muscle than magic in that party. 2 fighters, 1 spell caster, 1 half fighter/spell caster (the cleric), and then the bard, which could also kinda be considered a mix. Bards may be useful in BG1 because you can't get your saving throws too low (legitimately, that is), so they can help out. Some songs make you immune to fear, add a saving throw bonus, add combat bonuses (I guess it increases your 'to hit' roll).