Hi Alfredo,
Question 1 & 2: this link will help you - https://www.qualtrics.com/support/survey-platform/survey-module/survey-flow/standard-elements/embedded-data/
Question 3: Say you want to randomly pick up a number between 2/3/4/n then you can define that within randomizer in embedded data and let randomizer choose it for you which you can further make use in display logic or as per your need.
Hope this helps!

Alfredo Embedded data is any extra information you would like recorded in your survey data. Embedded data consists of a field and a value. The field is the name of your variable (e.g., Gender, State, Age). The value is what your field will be set to in your data. Just as one question can have multiple possible answers, an embedded data field can have multiple possible values (e.g., a field called Gender might have a value of Female, Male, or Other).

I tried doing Question 3 of picking 3 random numbers from a list of 50 using the randomizer but I couldn’t store all three values. I tried using multi-choice in the options for embedded data but it would only record the last choice. How do I get all three picks?