Nine Kavin at Home: How to shower correctly to fulfill the Halakha?

Hello, Honorable Rabbi, How many minutes does a shower of nine kavin take? And how should it be done: just stand under the shower for several minutes or adjust something, etc.? And pardon the question, is it permissible to use soap during this, etc.?

Hello and blessings 

1. There is no set time, and it is difficult to give a precise duration because each shower has different water pressure. 

Since the amount of water is 18 liters [and some say 10 liters], you can estimate it this way: a regular vessel for netilas yadaim is one liter, check how long it takes to fill the cup, and multiply by 18. 

2. Simply stand under the water. Ideally, you should stand with the shower above you. However, if there is no way to position it, it is permissible to hold it in your hand. 

3. As explained in the previous answer, ideally, one should stand facing the water and wash the entire body together, but if necessary, even if you move and act during it, it will be effective.