you can either use Courgette or bsdiff or some other binary diff algorithm for compressing code updates, or punt and choose to fully replace all of your code every time you rev.

update verification is a < 100-line block of code using system cryptographic libraries on Windows.

for Chrome-style background updating, the solution is as simple as:

1) running a thread in the background to ping an API to check when updates are available, 2) downloading them via HTTP when they arrive, and 3) having a program which gets run at update-required-exit, which verifies and applies the patch to your main executable.

yes, writing update machinery for your software is some work. no, it's not insurmountable, and will certainly get easier as the Mac App Store and Windows Store gain traction because they allow you to piggyback on the update machinery of the platform.