Do you recommend to delete the previous rankings once a new week is added..?..
Only if the calculation time is too long. Otherwise, I would just leave them. Reason: when you delete them, you’ll have to replace the shortcode for that ranking with the static html.
will this effect the calculation time when theres 60 users and we are well into a season or competition?
Yes, but it depends on your server config how big the effect is. I would just try and take measures only when needed. 60 users doesn’t sound like something that would cause big problems.
To show all users in the weekly table -is default all or do I have to enter the short code to select all players.?..
The shortcode always caps the amount of users. Default is 5. But if you want all users, just fill in 1000 in the parameter. That will at least work until your user base grows to 1000 ??
[fp-ranking ranking=4 num=1000]
I suppose the only other question is that is there a shortcode to extract the number of exact scores by users predicted into a table? with name and amount of correct scores.
No, not a separate shortcode. There is an extension* that puts this info in the ranking table. Maybe that is something that you can use. Either by default in all rankings, or hide the info in the other rankings via css and only show the info in the table where you want it.
* The extension can show the amount of full scores, or the total points from full scores. See template in the code for the value that is used.