About OutBound Links how to make - SEO ON PAGE

Hello,
I read that it's important to have links that take you out of your site, it seems that Google likes that.

But, I had some doubts about that. If you have some experience and you want to share with us I thank you immensely.

1. How to disclose a link to another site, other than for your own niche?
I think Google likes links that have to do with what I'm talking about, right? But, how to do this without helping my competition?

2. Do the links that leave my site need to be ******** or nofollow? If I classify as ******** I'm telling Google that the content of the link complements or does it relate to the context in which it was included?

3. How many outbound links does my page need to have? That is, links that are on my page that point to others. 1, 2, 3 ..?

4. I heard that PA / DA metrics are best suited to determine if that link I'm pointed to likes Google. So, which tool to use to quickly detect if the domain I'm trying to point to has good metrics?

Sorry my english, it was done in the translator