You always need to be sure your project is square. This tool can help you and you also have 4 rulers inside.
Check the technical drawing I did so you can see this tool's dimensions!
I almost always use standard settings as a starting point and tweak some parameters based on the filament I use or the characteristics I need from the final print. So go for the whatever profile you like, it will probably work anyway!
There is no need for support on this print.
Ask me if you have problems!