How big is the store? You could easily install a store, a blog and nodebb on one server. However the installation process would be a little more advanced than just upping the files and going to site/install.php, you would need to install the php modules and any other service that was needed by that software before installing your software, you would also, as you've said, need to route each connection to the correct place, Digital Ocean (link in my signature) has some great guides for installing popular software (except NodeBB, but I'm working on that). I've had Magento running on Digital Oceans droplets before and it works fine (however it is a bit resource intensive, so I'd recommend the $10 package if that's the platform you were thinking of.)
I don't want to go into each ecommerce platforms and their pros and cons until I know what sort of thing you're wanting but I've helped no end of ecommerce companies achieve what they're after. One thing I'll note though is, nodebb and ghost are so lightweight, that you'll rarely notice them compared to an ecommerce platform. Feel free to message me via chat if you don't fancy giving away your trade secrets on a public forum.