I have installed your great component without any problem, two different "template" sites with some slave sites for both of them.
I have configured the "template" sites to create a specific image and media folders for each slave site. No problem, working.

But following the same procedure to create a specific template folder is not working for me.
I have followed the '/templates' naming restriction, and I get the folder but the installed templates are still pointing to the root directory and not to the specific folder. Therefore, if let's say I tweak the css of the template in the specific folder there is no effect in the template, as it is reading the css file in the root directory.

My goal is to reused the same template through different slave sites but with little (or big) css or html finetunning for each site. I know that I can just change the installation xml of the template and install each time in the master site as it was a new template, but reading your documentation I wonder if creating a specific template folder could be a solution.

Same principle applies for a component. If I want to tweak a component to work in a slightly different way for a specific slave site, should I re-install the component in the slave site or modify the installation xml of the component and install it twice (with different name) in the master site?

I have been looking through the forum for a similar question but didn't get an answer for me.
My server is Unix based, if this is important.

Thanks for your time and congratulations for a great piece of work.

You can create templates directory.
Read the users manual chapter 3.2.2 that specify some restriction (it seems you have read it).
When you are on unix platform, JMS create a "themes" directory in which it creates links to existing themes present in the master website.
Perhaps this is what you see when you have a look on existing themes.

Once you have provided a specific themes folders, this means that a slave site can install new themes that will be only present on this slave site.
You could try to install one to check that it is only created into the slave site themes directory only.
If this well the case, this mean that you could un-install the themes that you want to convert in specific in aim to delete the current Symbolic Link. Once it is removed, it should still available on the other website and only removed from this slave site.
You can re-install the themes that will become specific.

In conclusion, the key issue is to know if you use a symbolic link for the themes or if it is become really specific.

This information is helpful.

Could you also expand upon the Components question here? I also will be using components that will need to have files tweak to functions as desired. In particular, many extensions still bury CSS files in their own directories, and they will need to be modified.

Thanks!

If other extension are using CSS that locate image in their local directory, you may also have to modify those CSS to put the images path located in a directory that is specific to the website itself.

There is no miracle solution.
As soon an extension access CSS locally in their own directory, this mean that they will be shared as all the extensions share the PHP code (files and folders).
So you may have to adapt the CSS to access information outside their local directory.