Thank you for your answers!
> to consider getting someone to English edit the content for you
Yeah, content management and English is not my strong side, so I assume in real projects someone other than me will write texts. But thanks for advice, it's still a good idea to show my texts to native speakers so my portfolio works will look better.
> Regarding portfolios, this article offers some handy advice.
Nice article, thanks!
> Do I have to 'login' before I can see a demo?
Good question. I like it when I can see some demo before I sign up, but I forgot to add something like this to my prototype. Will fix it.
> I also think the landing page would benefit from some sort of navigation.
As I see it, landing page is for new users who visit this page to see what the product is. After you registered and logged in, you see different interface with different navigation. About landing navigation itself, I am not focused on it in this prototype, main goal was to show interface of a product inside. Of course, it might have some pages like support, manual, our customers etc. Maybe I should show them at least as links with descriptions. Yes, I will add some links.
> I'm not sure that the 'nice drawing of a crowd' adds value to what you are trying to achieve
It is just some idea of how it might look in my imagination. And yes, Im not sure too =). In fact I think it's a question that should be answered with a/b testing, like whats better, drawing or screenshot, "give it a try" or "sign up" etc.
Thanks again, I got some positive mood reading your answers, looking forward to make a nice portfolio!