Hi
@tazarbm, glad that my tips helpful for you
Let me answer your questions one by one:
1. There is no exact recommended number of pins from Pinterest officially as long as you can keep pinning consistently, this is what Pinterest wants. The number of pins you can pin will depend on your content if you have a lot of content, then you can pin like 5-20 pin per day. It varies for each person.
2. Currently, there is a new pinning limit from Pinterest. Here the case study, you can create 3 different pin image versions for 1 page URL, and save it to 3 relevant boards with an interval of 2 days. Do the same thing with other page URL with the same rule of thumb. Pinterest requires us the fresh image and new fresh URL content Yes, it's become more challenging if we just started to create our blog since Pinterest demands us more new URL content not only fresh image with the same URL like in the past.
3. Smart feed is the home feed of Pinterest when you open Pinterest apps from mobile and your laptop (desktop). It's the same as Facebook Feeds and IG Feeds, on Pinterest it's called a smart feed
4. If you want to join Group boards, you need to check the group board owners' Pinterest profile and go to their website and find their contact form or their email address, then email them that you want to be a contributor on their group board. Don't send them a message on Pinterest. You will get banned if you message so many Group board owner. Also, ensure before applying to a group board, you have claimed your website on Pinterest. Ensure to have at least 7 boards and have at least 25 pins on each board to show that your Pinterest account is ready to become a contributor on their group board.
5. Please kindly be informed that on the middle of 2018 Pinterest have been reducing the distribution of the pin save to the group board. I recommend you if you just started, you can focus on a group board with only 10% of your effort. If you want to join the group board, find a small group board with only small contributors. Don't join the big group board with a lot of contributors, they just spam and will hurt your pin engagement score.