Evolve Mobile friendly-Membership page or Signup form for Video

HI Everyone,
I try to learn and understand so much but get very confused sometimes.
Let me try to list some concerns and hope someone of you is not as confused as me ??
First of all I have 2 websites, but would like to continue with only one.
rachelsmets and ExpattoInpat
1/ Can anyone suggest how I can easily make use of a subdomain? I thought of adding page to rachelsmets site and there people could find the subdomain with all the content of the Expat website.
Is that realistic?

2/ I would like to have people subscribe their email and give a free gift, but NOT a document, but a VIDEO. I have mailchimp, but the video should be on a page on my site no?
I’m not sure how that goes.

3/ How can I create a membership page and how do people get there?
I know there are certain plugins for it, but if people need to pay for membership, how does that happen?

If anyone understands me a little bit, I would appreciate ANY advise in simple words
I apologize for asking everything at once and for being confused. I really want to learn.
Or if someone can help, that would be fine too.

Thanks again
Rachel