So is there really no point in getting Virelai since you can't control your pet?
Well, no harm in *getting* Virelai. It's only like 3k or something. Just don't expect to find much use for it.
It's a nice way of deathwarping after a colibri party though: virelai a colibri and land it, when it comes uncharmed the colibri will learn it and cast it back on you, and if you're lucky enough that it doesn't resist (they seem to be rather worse at landing that than landing elegy or lullaby, sadly), *you* are now the *colibri's* pet. Which is, in and of itself, kinda fun. At this point your party members can kill you off, you can HP, and you don't lose exp for death while charmed.
But yeah, overall it's really kind of a toy spell. Still, like I said, it's cheap, so there's no harm in getting it. Just don't waste money on the instruments for it.
This mean that there will still be some uses for string equipment. Now here come the question. How come people rather get wind + skill like wind earring, wind torque and not singing equipment like singing earring and singing torque? You do not have to keep both singing and wind or singing and string equal for maximum efficiency right?
Well one reason is that in every slot except hands, one ear, and (if you count merits as an equip slot) merits, you don't *have* to choose. There's either a singing option there, or there's a wind option there. So, use both. Though you'll want enough CHR here and there to get your total CHR into the 100-110 range (bit higher for HNMs perhaps), and you'll probably want other useful stats like VIT/def/-dmg%/Haste (if pulling), max MP and refresh (if playing support role), -enmity (anything endgame), etc.
As for the spots you do have to choose: merits aren't a concern unless you have some or all of the magic skill merits earmarked for another job (say, RDM or something). Otherwise, 8 singing and 8 wind merits, done. Otherwise you have to choose: do I want more singing merits or more wind merits? Hands are also an easy choice: AF+1 (the singing option) trumps AF2/AF2+1 (the wind option) by a loooong shot. Even normal AF trumps AF2/AF2+1.
(Incidentally, slight side note: Limbus is arguably the single most rewarding of the current endgame events for bards. We have two awesome AF+1 - hands and legs - and one very good AF+1 - body. In addition, two of the 75-coin earrings are very nice as well.)
As for the earring slot that isn't taken up by Musical Earring, whether you wear Singing Earring or Wind Earring there is up to you. 3 skill either way. Or you could wear something else entirely - Loquacious is good for example. So is Novia, if you do jailers, for endgameish things.
There's no Singing Torque - only Wind Torque and String Torque. If you use string for anything, there's no reason not to get a String Torque: they *are* cheap. If, however, you don't, then it's -1 inventory. There are earrings for all three skills, as well as Musical Earring which gives 5 skill to both wind *and* string (not that it comes in handy simultaneously, but it works in either case so whatever).