Questions on Amazon Conversion Rates & CPC: Attribution & Bids for Private Label Seller

Hey everyone,
I’ve been selling a private label $40 wooden product on Amazon for about 6 months now (not really an impulse buy). I’m running at about $8k in monthly net revenue. First off, thank you all for the advice and support in this community! I have a couple of questions based on what I’ve been navigating:

1. Conversion Rate Fluctuations & Attribution Window: Some days, my conversion rate drops to 2-3% (my average is around 8-9%). I’m wondering if these low days are because people are clicking one day but actually buying later. I am generally aware of the PPC attribution window, but I don’t fully get how it works in practice—especially since, when I check my campaign reports after the 7-day window, I usually don’t see later sales being added in. And for organic sales, I have no idea how (or if) I can check this. Any insights on how attribution really works for both PPC and organic traffic?
2. CPCs as Product Gains Traction: I’ve heard people say your CPC should go down over time as the product gains traction. Is this something Amazon does automatically (charging less for the same bid if your relevance/quality improves), or do I need to reduce my bids manually to actually get a lower CPC?

Looking forward to your experiences and advice! Thanks in advance.