Don't worry about the checkerboard pattern if it always goes away. Unlike later models, the Plus analog board doesn't have a congenital problem with caps, so this recapping business is not the first thing to consider here.

The memory test is indeed causing the extended boot time. If you're impatient like me, and don't want to wait, boot with the mouse button held down. That bypasses the memory test altogether. You can release the button as soon as you see it enter the normal boot sequence.