He probably think "melle" like phy/melee (not ranged) attack
I have 53 lvl full str and he do great crit for now
With int bow you will have nukes which do great dmg, but you will have low hp.
Str bow usualy use fire/light/pach, and int use light/cold/pach
Fire is great for phy attack increase and cold is great for nuker defense.
Choose what you is best for you.
Answer on your q is:
1. Full str if you bot and if you like great hp and crit, int if you like nukes and great damage, and non bot (usualy die alot)
2. If you are full str then better is attack mobs with phy attack because you have great phy defense. (full int, great mag def so you can attack mobs with mag attack)