I’d suggest you to download the SD card image from this site https://communities.intel.com/docs/DOC-22226, extract the content into the SD card, if you it on FAT 32 the image should start the booting process automatically as soon as you power your board. Then you need to enter in the Linux side, there are several methods, the simplest and in which you have access to the booting process is though the serial console cable. If you are using a Galileo Gen 1 you can make your own cable by following this post http://www.malinov.com/Home/sergey-s-blog/intelgalileo-introduction . If you are using a Gen 2 you need an FTDI cable, the specs and a comparison are listed in this doc https://communities.intel.com/docs/DOC-23043. Other methods to get into the Linux command line are explained in here https://communities.intel.com/thread/46335, but I would suggest you to go with the serial console cable. Now for image processing you can use OpenCV. To install it you can use opkg which is a package manager, follow these steps to learn how to use opkg http://alextgalileo.altervista.org/package-repo-configuration-instructions.html and http://alextgalileo.altervista.org/blog/installing-development-tools-onto-official-linux-image/ . AlexT's repo is very useful and includes OpenCV please check it out, is included in the link that says “package repo configuration instructions”. Regarding running sketches in parallel to other programs in Linux, it is possible, you can create a program in python and execute it while running an Arduino sketch. I’d suggest you to read some documentation on Python and OpenCV for more detailed information. Also check Sergey’s blog http://www.malinov.com/Home/sergey-s-blog it is really good, in there are some tutorials on how to configure the GPIOs, setting up a wireless connection, GPIO mapping and more. I hope I’ve covered all your questions. Let me know if this is what you are looking for.