You don't need to do DT, but it is an enjoyable quest and you'll need it done sooner or afterwards, and doing this RuneScape gold now would be helpful. As you don't need then, 70 att,def,str,array and mage will help considerably. You really, really, really do not need them. Barrows runs work fine without them. I'm confident that 70 defence may help a bit, but if you're utilizing ice magics, then you never should melee anyway. At all. Karil gets ruined by magic and ahrim is just a bit slow to range.
Admittedly I do not normally do over 1 run a moment, but that is because I can't escape from the maze. (This was before I got some of the levels you explain ). I know I could do two or even 3 runs in a stretch. 70 defence is quite very very helpful with blitz into sally, which is among the Old school rs gold greatest methods(in case you don't have access to turm/chaotics etc etc). Attack and strength speed up ahrim, however isn't necessary and 70 mage is a minimum, 82 is better.