Should I fix my build errors as soon as I get them ? Or should I (let's say) try to fix all of my errors every week or so ? Or should I just code the majority of my app and then try to fix all the errors ?
In other words, how often should I be trying to fix all of my build errors ?
I would consistently try and fix errors as you find/create them, and focus on making a compiling and running application with each individual change you do.
If you are using version control, focus on making each change set a running application, even if some of your stuff isn't finished yet.