Facebook Ads Success Metrics – DB

I need help please with evaluating my Facebook Ads. Just started running them on September 11th (with some help from an ads manager).
I’m running adds to a freebie. I feel like the ads are working well, all under $2 per conversion but I’m not sure on my email sequence open rates. My goal for the ads was to test my freebie, build my list, build rapport and eventually lead to mini sessions.

Here are the stats:

Email # 1-delivery of the freebie: 67% open rate on the email but only 34% click on the link to actually get their freebie (it’s a PDF and an accompanying video)

Email # 2 – has an open rate of 47% – I deliver extra value in this email with an audio that helps them take action on the freebie if they haven’t yet and gives them extra tips

Email # 3: I give tips and also offer mini sessions. At first, open rate was less than 10% on this one and I just changed it and it’s improving. No clicks to the link for the mini sessions.

Email # 4: offers value and also social proof with a success story from a recent client. I offer minis in this one too. Open rate is 26%. No clicks to link.

So this is the math and I have 3 questions :

1- Are these open rates and clicks (no clicks) normal? The numbers are small (70 new subscribers) but wondering if this is normal?
2- Anything I should look at and potentially test?
3- Overall, I’m not sure what guidelines to use to gauge if the ads are working or not working?
4- Should I consider retargeting ads to the new subscribers and if so, I’m not sure what to offer them?