There's a few factors to consider here from a pure damage perspective:
- arrows, which provide your base damage dice
- the bow, which provides a damage bonus
Since you said you were going to use the Quiver of Plenty, that means +1 arrows (1d6+1) as your base damage. You can upgrade the Quiver to give you +2 arrows (1d6+2).
There was a bug where the +2 damage for those arrows wasn't applied in
BG2. I don't know if that bug made it to BG:EE or was fixed.
If it is still in BG:EE, upgrading the Quiver is actually a damage downgrade
(although the to-hit bonus still applies, so it's probably
Bows are the fun part.
Most of the interesting and powerful unique bows aren't available until BG2. The Dead Shot, a +3 longbow, is probably what you want for just Baldur's Gate 1. It adds +2 damage.
However, if you're going to play through into Baldur's Gate 2, the Gesen Bow is probably the most damaging, adding 2 piercing and 1d8 electrical. As an Archer you can achieve the grandmaster proficiency in longbows and shortbows, and you'll eventually get enough points to do so for both types, but not until you're pretty high level.
Grandmastery gives you +5 bonus damage, and you'll start with four points to spend at level one, so you can get there pretty early. If you want to be more powerful early on, focus on long bows and The Dead Shot. If you want to be more powerful in the long run, suffer through BG1 with the Short Bow +1 at Grandmastery and get Gesen's Bow as soon as you can.
You may also be interested in this thread on Archer damage calculations, although it is based on BG2.
As for other gear, there's not much that you can do that's going to be better than your current load out (even if you weren't forcing stats to their cap of 25 without gear bonuses). There isn't much (any?) great that adds +damage, and only a few pieces that increase damage output through improved stats (and most of those do it by setting a stat to a fixed value like 18/00 or 19, which you're already exceeding).
You've picked the same helm, armor and gauntlets I'd suggest.
The Greenstone Amulet provides a check against a wider variety of status effects, but must be used to to do (whereas the Periapt provides a passive immunity). The Periapt is supposed to only be in BG2, but I guess it ended up in BG:EE via the back-porting processing. Likewise the Belt of Inertial Barrier. If that is an issue for you, I'd suggest swapping the Periapt for the Greenstone Amulet and the belt for any of the other three belts that offer protection against piercing/slashing/blunt weapons. Possible all three as per the situation, because why not?
The Rabbit's Foot isn't that good, sure it's got an AC bonus but you shouldn't be in the thick of it. It's technically only supposed to be usable by Alora. You might consider replacing it with the Ring of Free Action because being immobile is bad for you.
The Ring of Protection +2 is a good choice. If you want an opportunity for more damage early on, when you don't need to be so concerned over your saving throws, the Ring of Energy is a cheap attack. But your bow will likely out-damage it quickly, and be easier to use, so I'm not sure what else to suggest there.
The Boots of Speed are a great choice, but they can make you dash ahead of your party members which is both annoying and can make you more vulnerable, since you won't be behind your tank wall. If that becomes an issue, try the Boots of the North, of Grounding, or of Avoidance instead for some extra protection.
The Cloak of Reflection seems situational. Certainly useful for casters spamming lightning bolts, but otherwise maybe not so great? Consider the Cloak of Balduran for the saving throws, or the Cloak of the Shield for some more AC bonuses.