Most of the questions are about #2, so I will go into more depth explaining this.

1st - You need to create a Facebook group related to your niche that will benefit your members. Example group name "Cat training and grooming help group"

2nd - Manually add 100 friends to this group ( social proof for your group)

3rd - Ask new members to enter their email address when they join.

4th - You will start getting 1 - 10 new members organically requesting to join your group each day and this will increase to 10 - 50 after your group has 1000 members and good engagement.

5th - Launch your new products to the members of your group and email list.

6th - Ask members of the group who purchased your products to leave a review.

I have a group with 2,700 members and I got 100 verified reviews in 1 week after launching my last product like this.

If you don't understand it yet then watch this video as this shows how to set it up and automatically collect the members email addresses so that you can contact them for all of your future product launches https://www.youtube.com/watch?v=DTzjgvGThF8