Slayer Questions

1) Is the DPS for Duel-wielding chaotic crossbows and royal crossbow equal?
2) Are weaknesses that important? I don't have the resources (either GP or DG tokens) to get a good quality weapons for category of each type of combat. I already have a chaotic staff for magic, chaotic maul (ugh why did I buy it lol, that was forever ago) for crush, and a chaotic rapier for slash (though I need to buy an offhand). Now I am wondering how strong I need to stick to monster weaknesses. I am trying to mage as little as possible, and put more priority into ranging and melee.
I am not planning on using arrows/thrown weapons, I think I will stick to bolts. For melee I am less sure. I have around 280K DG tokens. I have a crush/stab weapon, but no offhand stab weapon. What is my best course of action? I could either buy an offhand rapier and those rapiers for both slash and stab, or I could use a GS for slash, or I could buy a chaotic longsword and get two medium-bad offhands.