LUG Krefeld: EntwicklerFragen

Vi vs. Emacs vs. graphica editors/IDEs: which makes me more productive?
Should language developers spend their time on tools, syntax, library, or something else (like speed)? What makes the most difference to their users?
Do unit tests save more time in debugging than they take to write/run/keep updated?
Do distribution version control systems offer any advantages over centralized version control systems? (As a sub-question, Git or Mercurial: which helps me make fewer mistakes/shows me the info I need faster?)
What are the best debugging techniques?
Is it really twice as hard to debug as it is to write the code in the first place?
What are the differences (bug count, code complexity, size, etc.), if any, between community-driven open source projects and corporate-controlled open source projects?
If 10,000-line projects don’t benefit from architecture, but 100,000-line projects do, what do you do when your project slowly grows from the first size to the second?
When does it make sense to reinvent the wheel vs. use an existing library?
Are conferences worth the money? How much do they help junior/intermediate/senior programmers?