subjunctives - whether it be vs whether it is

I brought the sentences from the speech about conversation tips.

They don’t just want to know about news and the weather.
They want to know about you.
So what are three things that you have going on right now, that you can talk about.
Whether it be school, whether it be a personal relationship, whether it be a hobby that you’re involved with.

My questions:

1. 
   
   

   What is the difference in nuance between 'whether it is' and 'whether it be'?

   
   


2. 
   

   Before posting this question, I googled, and some websites say 'whether it be' is subjunctive. I don't get why it is called 'subjunctive'. Because from what I know about subjunctive, it's supposed to be past of be verb.

   
   


3. 
   

   If I say 'whether it should be' or whether it would be', is the meaning same?

   
   

Answer

Whether it be is subjunctive because it represents a conditional, as in the speaker does not know your life and what you will talk about. Whether is a conditional word so it causes the subjunctive form of verbs which tend to look the same as the infinitive form.

However, in common usage, whether it is is also acceptable. It is, however, not considered as formal. In truth, you can use the subjunctive or present form after whether and both will be understood.

i.e. "Whether it run fast or slow." and "whether it runs fast or slow."

The present tense form is, in my experience, more common.

It seems that the subjunctive is more common with very common verbs like be or go, as well as modals like can or shall.