I haven't found any hardware errata yet, just a truckload of missing, poorly written, or conflicting documentation. I'll provide you with a rough workflow that I've followed to get started. Feel free to ask me any questions.
Step1: Grab the Arrow lab material from the following link and work through them on Quartus 13.1. They're written for Quartus 13.0sp1 but they can be followed on Quartus 13.1 without issue. The only additional step is upgrading the IP cores from those packaged with 13.0sp1 to those packaged with 13.1; this will be done automatically when the sopc is opened in Qsys
http://www.arrownac.com/solutions/sockit/files/SoCKIT_Materials.zip
Working through the hardware side will get you a usable sof file to program the FPGA. Working through the software side will get you a usable preloader. Although the SoCKit is heavily based off of Altera's reference development kit (GHRD) the preloader is different in large part due to slightly different SDRAM specifications. Attempting to use the preloader included in Altera's SoCEDS will not work.
The programming stage of the documentation is a bit flawed. The reference configuration assumes a single JTAG device, but there can be more. At a minimum there will be one for the HPS, but a bank of two dipswitches on the board can enable JTAG for the HPS itself and any devices connected via HSMC. Just use autodetect to pick up all JTAG devices and program the SOF file to the FPGA device, it's very clear as to which is which.
Next, grab the github repositories for the linux-socfpga (kernel), poky-socfpga (base filesystem), and u-boot-socfpga (bootloader). Grab the latest version tagged with '-rel'. I used the following:
kernel: socfpga-3.9-rel
u-boot: socfpga_v2013.01.01-rel
poky: danny-altera-rel
The wiki on rocketboards can be followed to install the dependencies and begin compilation. I can verify that everything builds nicely on CentOS 6.5 without much fuss, Ubuntu is extremely problematic so I would avoid it.
If you look at the SD Card image that ships with the SoCKit you'll notice that it has a FAT filesystem with two files on it, socfpga.dtb and uImage. These are the device-tree-blob, and linux-kernel-image respectively. The kernel is in a u-boot image format, which is simply a zImage with an additional header. The bootloader that ships with Terasic's SD card image uses an early 2012 version of u-boot and does not support booting directly from a zImage. Support for this (bootz command) is present in the 2013.01.01 release of u-boot so it is no longer necessary to attach the additional header to the kernel image. Just configure and compile the kernel as a zImage as they do in the wiki.
An additional step is missing in the wiki (at least it was last time I looked). The dtb is tightly coupled to the kernel version. Using a dtb from the terasic reference SD image will work for kernel version 3.7, but it will not work for kernel 3.9 or above. The reference one created by Altera's sopc2dts tool is crap and won't work either. However, a working dtb has been included in the linux-socfpga tree under arch/arm/boot/dts/socfpga_cyclone5.dts. This can be compiled to a dtb either through the dtc tool itself, or in-situ by running 'make ARCH=arm dtbs'. This is good enough to get started with, but if you add additional memory mapped devices to your system you will have to modify it by hand and recompile it.
NOTE: the socfpga_cyclone5.dts file exists in the 3.9-rel tree, but has been replaced and expanded in master by one specifically tailored towards the SoCKit. I haven't looked at this yet, it's on my todo list. You may wish to check it out.
OTHER NOTE:The bootloader will look for socfpga.dtb by default. You can change the name of the file that it looks for by tweaking the bootloader environment settings (this is good practice) or you can change the name of the file when you copy it to the filesystem.
Expand the compiled root file system tarball into a folder called rootfs. You must do this using sudo. It seems like a needless step.
Gather the compiled u-boot.img, zImage, socfpga.dtb, preloader, and rootfs directory together and run the tool to make the SD card image. Write the SD card image to an a SD card, insert, and powerup. Open a serial terminal at 112500 baud (57600 for older versions of u-boot) and watch the boot process. Hit the soft reset key to start the process over.
OTHER OTHER NOTE: This is mentioned in the documentation, but deserves mentioning anyway. If the system is configured to boot via Active Serial 4x it will load the FPGA image from the EPCQ256 which due to a bad default image will prevent the HPS from initializing. Supposedly this can be fixed by overwriting the EPCQ256, but the best way is to actually program the FPGA from a file stored on the SD card. This can be done through u-boot directly but I haven't figured out how yet (yay documentation...)
That should be enough to get you started. If you see no output or it hangs before u-boot has loaded, then the preloader is incorrectly packaged or misconfigured. Make sure that you didn't skip any steps in the tutorial.
If you get to the u-boot command prompt (interrupt the autoload) then your preloader is fine.
The next step is to load the kernel. just type 'bootz' (or let it autoboot) and watch the magic. If it says "Bad zImage Magic!" then there the dtb file is not correctly compiled. If it loads but hangs before running init then the dtb is compiled but not compatible with the kernel. Attempting to use a 3.7 dtb with the 3.9 kernel will at the very least result in the MMC failing to respond. u-boot can read it, and can thus load the kernel into memory, but the kernel itself cannot read it.
I hope that this helped a bit!