Yes, I did find a solution. Thank you both for your concern.

Hope you found a solution!

There can be some problems in Mailchimp. Some with solutions are described here:
http://kb.mailchimp.com/lists/signup-forms/my-subscribers-dont-receive-confirmation-emails-when-they-sign-up

I have Sumome and I am very happy with it.

Many in WA use SumoMe for this share display described here: https://pagely.com/blog/2014/10/sumome-social-sharing-buttons-free-audience-growing-tools/

You can use Social Media Feather plugin. It has all of the social media you mentioned.

I was just about to ask that question...

Thanks for this question. I've never heard a landing page called an opt-in page before. Here is a good helpful source: http://aureliustjin.com/how-to-create-a-killer-opt-in-page-in-10-short-simple-steps

Exit pop-ups work well. I've got one on my website which is doing quite well.

Hey Melania, this training from Marion is helpful : How to Create Your List for Free

Thank you John!!! I sincerely appreciate it.

Here are a few plugins that create landing pages. https://wordpress.org/plugins/tags/free-landing-page-templates
I also use Optimizepress, but you can also create a landing page, just by using a separate page on your site.
Google "landing page examples" to get a bit of an idea what to do.