HELP: Total Organic Visits vs Total Organic Searches

Hi,

I have been searching for an answer for hours, but till now to no avail. Therefore, i came here to see if anyone can answer my questions in layman's terms.

1. Is it true that Sessions & Visits are the same?

2. What does the "Organic Search" metric mean?? (Refer to screenshot) I feel that this description "The number of organic searches that occurred within a session" is vague and confusing.
Does it mean, for instance, I search for "nike shoes" on google & i enter "Nike Homepage" (One session is created) Then, i click "back" button to return to search results, scroll down and i click another link to enter "Nike Shoes" page. As it's still under the same website within a time frame of 30 minutes, so am i right to say
No. of Organic Session: 1
No. of Organic Searches: 2 (Since i click on 2 different links on Google to enter the Nike website)

3. Total Organic Visits

Scenario A:
Ok so now i either have 2 Google Chrome browser windows or 2 tabs opened in one Google Chrome browser (Guess it doesn't make a difference?). One is Yahoo search engine, the other is Google search engine. Based on the previous example, i enter the "Nike" website on both Yahoo and Google in 2 separate windows/tabs. So, in this case, is this counted as 1 or 2 organic sessions?

Scenario B:
I enter the Nike Homepage via Google. Somehow, i decide to search using Yahoo instead so, i change the URL from google.com to yahoo.com and perform the same search and enter the Nike website. So, is this counted as 1 or 2 organic sessions?

If you guys see the screenshots, you will notice the Total Organic Visits are more than Total Organic Searches which i feel it doesn't make sense.

I appreciate if any gurus can help me with this. Thanks a lot!