Relatively new player - Following a guide dependent on Quill Rain....

So, I was following this guide as my Betrayal league starter, but seeing as how this guide is very dependent on quill rain for endgame, are there any suggestions for changes I should make that anyone can help with? I'm not very keen on the economy or items in-game, I wouldn't really know where to make adjustments.

I've been reading about the new chaos damage over time multiplier's on the passive tree, should I aim to rework this build and head toward those? Currently level 59, will be hitting maps probably in the next day or so (act 7). I haven't hit any leveling roadblocks with the bow yet and it's still a very viable leveling item IMO, just looks like it's lost it's endgame touch.

I think you should be fine using Quill Rain till late endgame.

You can try Storm Cloud with top attack speed roll later eventually as cheap alternative (should be better DPS wise).

There are also +3 bows as an option for late endgame.

New chaos damage passive multipliers (there are also some items) are worth taking but it requires some changes in passive tree (try to ask in the thread or see similar builds on poe.ninja).