I'm getting ready to move development of a site from XAMPP to a hosted server and couldn't find any concrete info on what I should set file permissions to after I unpack the gz.zip file into the server and what privileges the MySQL user I create for Silverstripe will need. Does anyone know where I can find this information.

Running locally none of this is an issue but I understand that on a production server it's good practice to restrict permissions and privileges to only those that are needed.

If you install SilverStripe the installation form tells you what kind fo rights you have to tweek. Besides, I would just copy the XAMP installation to the server and migrate the db. Make shure that you get the .htaccess for it is hidden by default. Delete the content of the foulder "silverstripecache" and flush database and template cache.

Good point, but the installer doesn't tell me if I have the rights set too liberally.

I also prefer to build from fresh installs when possible to limit copying errors (mine or the computer's) and to make sure I don't carry over any development detritus like unused files, obsolete tables and fields, etc. It also forces me to go through a process that makes it easier to know where bugs are coming in if a problem occurs.

If you have so much time you can go the long way. Of course you have more overview. I have to count the hours I spent on a project. The less time I spent, the more I earn.
I never had problems copying one of my projects. I don´t care if I loose 500 kB serverspace by copying obsolete files or tables.

I count my hours too, and aiming for maximum efficiency is a good thing, but in the right market the extra time those steps take can make up for the loss in total work by justifying a higher rate.

And, on my own personal level, cutting little corners like that feels... sloppy. Like making a custom piece of furniture for someone and turning it over with a few rough edges or poorly fitted joints. No one but an expert may ever consciously notice but little details have a way of making a difference.