don't hurry to kill the RoB. if you're really really intent to doing so, check out "how to kill a legendary" for tons of advice. at your current level it won't be cheap/quick imo.
You'll probably need:
spark of life to stop any of his hard hitting special attacks that normally one shot you. (only available through scrolls until you get to level 100. you can use scroll of life or scroll of gods)
*someone correct me if i'm wrong* but absorb does not have a 100% chance of blocking the spell (from scroll). but if it does, that would work as well.
you can do the stun/poison/haste if you want. the process is pretty slow and you'd probably kill the boss faster than its-just-me since your magic rating should be higher than what his was (hence your poison would be stronger)
in which case you would need a 30stun mace or 2x 24+ stun clubs or a 24+ stun club and a high block shield. tmihor has a pretty nice 24+ stun club with mana steal last i checked. only selling it for 1000C
weaken is really useful for boss fights since they all hit pretty hard for their level. bewilder is useful against manbearpig but i'm not sure if it's useful against the rest.
infusions speed up the killing process but imo, monster weaknesses are here:
http://ehwiki.org/wiki/Bestiary#Bossalways keep yourself nice and healed and you should be fine.
if you want to go maging:
with your current spell set available to you, i think the only bosses you'd have a decent time against is manbearpig via maging. tier 2 spells help a lot vs boss fights.
ideal for your circumstance is to probably have about 25+ extra elemental proficiency from gear and maxed out flare/meteor
difficulty setting -> normal
make sure your status -> great
have spark of life
use infusion of their elemental weakenss to boost your spell dmg
shadow veil/haste on yourself
weaken/bewilder on manbearpig
fire-eating gear if you want to play it safe
don't be cheap with the potions. carry greaters or higher (they cost nothing compared to the scrolls you'll be using)
your meteor should cost 7-8 mana. which should allow you for 20-30 casts on him *before* he's Coalesced Mana-ed. (50% discount oce he's Coalesced = go crazy on the meteors!) don't bother with ether-theft imo. at your level most ether thefts will last 1 turn at best and i'd much rather keep the guy perpetually coalesced in this scenario
keep your hp high so you don't get killed by his melee hits (weaken should stop him from crit-ing you)
there are tons of ways to kill the bosses. most high levels eat them for breakfast and consider them weaker than some of the custom mobs kicking around. i personally didn't attempt RoB until i was 100 <- then i could cast my own spark! was definitely a breeze on normal.
as for your stats, i don't think i can advise you on that. someone else will hopefully will. i'm currently doing this for stats though
str/dex/agi = 10 points lower than int/wis/end