> If there any way how we can hide the content while it not ready under some preloader?
This isn’t currently a feature, but we’ll look at something like this in the future. For now, I can just suggest not using the full-width feature if it’s not working in the way you want.
> Do you have some guid how to use Duplicator?
Here is the Duplicator user guide – https://lifeinthegrid.com/support/knowledgebase.php?article=3
> Also, what is you best advantages of the composer?
I’m not quite following this question, but I guess I can answer by saying our plugin is free. So you can try it out and see if it works for you. We’ve also focused on keeping things clean and simple so it’s very easy to learn.
Plus we have some very detailed documentation – I even recorded an introduction video https://siteorigin.com/page-builder/documentation/