Customization of a template - a few questions


I’m about to customize a template, and I have a few questions regarding the whole procedure after reading both wiki and FAQ.
I have read, in order to customize it, a hardcoded script style is needed.
However, instead of proceeding this way, is it possible to duplicate a default template (And then renaming it, for example, default-two.php), and then duplicating a custom.css (custom-two.css), linking it in the head of the duplicated template it and using it to customize the whole template?

Thanks in advance for your support.

Awaiting for your reply.

Most likely yes, that’s possible, but only way you can find out is by executing it.
Then you’ll know for sure.