It's been long time since I discovered Facebook pixel, however, I haven't had time or courage to find more about how it works and learn how to use it and make use of the data it does provide.

Can you please explain scenarios in which you use Facebook pixel, how do you implement it, and what data do you check when using it. How does it help your business?

If you have some good references to learn from, I'd appreciate if you could post links. Free materials preferably.

Thank you

When would you use 303 redirect? I often use 301, sometimes 302, but I have never used 303. What's the use case for it?

My website consists of several hundred unique (product) pages. However, Google shows only 80-100 indexed pages. Is there any way to force Google to index all of the website pages?

I am sorry if that's newbie question, but it's annoying and nothing has helped yet.

Do I need to add http://www.example.com, https://www.example.com, http://example.com and https://example.com? I have all of these defined in nginx server and redirecting them to https://example.com, not sure how to handle that in search console though.

It would be great if we could monitor the website in one place without adding all the alternatives. Is it possible?

Is Let's Encrypt certificate equally good for SEO as any other certificate money could buy? I am about to launch my new website, but I am still not decided whether should I use Let's encrypt or buy something from certification authorities like Comodo?

I am curious, how big is the difference between keyword rich URL/URI and one made up from random sequence of characters, like product number/code. Does it matter enough, so we should consider switching over to a completely new URL structure, or it's just not worth the hassle?

Our site is 6 years old, and over the time, there are many articles (up to one thousand articles actually). Our main source of traffic is organic search traffic and I don't really want to screw that up. It took us 6 years and quiet a lot of money too.

Thanks guys.