mechanical tuners broken

Sir, I own a 10 yr old dean edge 4 string bass,I was changing my e string and heard a snap, the tuner finger broke. And the shaft of the tuning key looks bent. First, is it recommended to replace all at once or one at a time? Second, what brands are good? Third, is this something that a person with mecanical back ground can change? Or is it better to have someone else?

 

Thank you, sounds simple.