Crossbows are always ready-to-fire once per action. Reloading takes place immediately before firing as a free "interact" action, similar to drawing a sword. So you still retain a bonus action and your movement. So, yes, you can fire the crossbow once each turn as long as you have ammunition.

How do you use the crossbow in D&D 5e?

You can load a crossbow once per Attack action regardless of the number of attacks you are allowed to make in that action. Any round in which you do not make an attack, you can use an Attack action, or your free “interact with one object” activity to load a crossbow.

Do crossbows use Dex or Str?

The answer below seems to back my findings, crossbows do add Dex modifier to damage.