I am not sure where I read it, but squash bugs won't cross Borage.
Also, to attract toads, you can burry a planter half way. They will crawl right in there! You can also dig a furrow/hole, and then find some thick bark and place it over it. If you want to spend money, you can buy toad houses. I have heard that toads eat TONS of bugs.
I know that if cucumbers and melons are planted next to each other, they will be bitter. I am not sure if this is true with melons and pumpkins.