signing free agents is also part of building a team. The salary cap, especially now, ensure you can't just outspend everyone to buy a championship team. All teams are built, not bought.
Yep. There are several ways to build a team, including through free agency.
Some folks talk about signing FA's as taking the "easy route" without considering that there is more to that than just "signing a bunch of names".
We've seen teams spend a lot of money on a roster and fail because they didn't consider "fit" when signing them.