Question 1 - As far as I am aware, three is no limit on the SSRS side, but there is a limit in how long the URL can be - 2,048 characters. As SSRS is a web-based tool, that means the full URL must be less than 2048 characters as well.
But if it works on your dev environment, it should work on live unless your dev URL is shorter than live (such as "http://dev.corp.com" for development server and "http://livereportingserver.corp.com" for live, then you MAY run into problems. But just keep the URL under 2048 characters and you should be fine.
Question 2 - Now, Visual Studio, and I expect report builder, still has the limitation where you can't create subfolders, so working with subfolders can be annoying if they get very deep as it is hard to organize it in Visual Studio.
Question 3 - there are powershell scripts for this (you can google them... there are various ones out there). As far as I know, there is no TSQL for this. There are also tools available for this. This website has a LOT of good information on it:
I recommend the DBATOOLS powershell module for this task as it is supported (unlike some of the tools they suggest), and gives limitations and suggestions for each method. Pick the one that you are most comfortable with AND that you can live with the limitations of (such as losing history). I strongly encourage you to read through the whole article before copy-pasting some of the scripts OR downloading tools as it has a lot of good information in it.