Some question

1. If you are eager to max her up immediately then farm the remaining mats now. But the saber pillar still has some neat drops + excellent QP, so it is always a good idea to farm pillars when it is available to stock up. That being said, we are not going to get some event for awhile until moon goddess revival (which I don't think has good crystal/hero proof), so you could still farm your mats after you get Musashi.

2. 65 apples each... that is kinda overkill for just the remaining pillars. Chances are you will have too much of a surplus of certain mats at this point. Just use apples until you stock up a good amount (especially fur and dust). I personally farm till I got extra 50 furs and 250 dust only. Though if you have a lot of time, feel free to use all your apples, not like there is any near future event that is worth spending apples for.

3. Next banner, in a week.

Edit: almost forget - good luck and hope you get Musashi.

The pillar is a good deal since you get materials and a good amount of qp to use the material with. Next best apple event will be nerofest this summer, so you will have time to save up more apples.

Musashi should be here new years, so if you are done with the pillars you can go farming proof of hero and crystals elsewhere since that pillar is destroyed.