How do I get users on my live video calling service - kind of like clarity for dog?

Why do you need them to be? Do you intend to deliver the courses under their name? And you feel they're not or they said they're not? Have you talked it over?

We've used MeetingBurner with success for our webinars. The price point for a large audience is not too high. It also has recording and automated webinar capabilities.

Cost of customer acquisition will depend a lot on what type of course you're looking to sell and your target audience. No one will be able to give you a straight up answer here. If you're able to provide more details, I could give some more nuanced advice :)

Investors do not fund ideas. You must prove significant market interest in a product. Statistics that highlight potential don't translate into your product's revenue. Investors want to see how they will get a return on their investment. As for a business plan, be mindful that this is an investment document that in addition to a narrative must contain solid CPA-driven financials. Investors also want to see that you have put more than thought into a start-up before they invest. Need a way forward? I'm happy to assist.

If I was you I would contact the guys from Altschool that just started one, and can probably help you with it. Contact on Twitter @rubenharris he can probably help you.