LOL at Dreamer, Downunda and fable
Stat wise use:
STR: (not import to an archer but remeber you will need to melee sometimes)
DEX: (max it out, 19)
CON: (max it - 17 or 18 depending on class)
Use an elf as they recieve bonuses with weapons.
Use gauntlets of weapon skill/expertise/specialisation to improve melee skill because remember archers can only become proficient in a weapon.
Use girdles of strength to improve melee.
Use shadow dragon scale in SoA, white dragon scale in ToB.
Use Strong Arm +2 in SoA and ToB (not the best THAC0, but the most damaging bow in the game and you can get it right at the start of chapter 2 from Ribald. Remember THAC0 is going to be excellent with a solo archer - they will level up fast and recieve frequent bonuses.
Keep a large sword nearly for melee Lilacour/warblade SOA, Gram ToB.
Use a cloak of the sewer at start of SoA, then use mirroring, then Montilo in ToB.
Use amulet of 10% resistance in SoA, Seradine in ToB.
In terms of RoF, the only bow that can improve this is Tuigan Bow+1 with 1 extra APR. An level 13 archer will attack 5 times with boots of speed anyway (with original grandmaster patch).
Hope this helps
Jim