PoTD floors 1-50 is very different from floor 51+
First, your PoTD character level is different from your actual character level. You start floor 1 of PoTD at character level 1 no matter what you have outside. Until you reach level 60 in PoTD you do get xp from kills. So while running floors 1-50 I would try to kill everything until you hit level 60. Your weapon/armor bonus matters more but having those extra skills can be very useful depending on your class. After you reach character level 60 the kills don't matter any more.
Once you've cleared floor 50 you can then start any later runs from 51. When you start at floor 51 your PoTD character level starts at 60, so again kills won't help at all for xp. This is where you just get a lump of xp for each 10 floors cleared - like 500K.

Regarding the 230 weapon, if you get your weapon and armor bonus both up to +30 you can talk to one of the NPCs outside to get an ilvl 235 "padjali" weapon for your current class. Doing this lowers both bonuses by 30. If you then get them back up to +60 you can upgrade the padjali weapon to an ilvl 255 "kinna". This lowers both bonuses by 60.