Actually, I didn't know. I just knew that it's better to check out that stuff before starting to spend money.

I have done enough modifying bikes to know that starting with an appropriate frame is big in both minimizing frustration and minimizing the project cost. There's lots of little bits and bobs like chain tensioners and clamp on cable stops that you can buy, but they tend to be relatively expensive, sometimes hard to find, and can nickel and dime a project to death. It's so much easier if you start with a frame that doesn't need any of that stuff.