If you use Kdepartitionmanager, you may recreate your partition table as MBR. It's not a partition "per se", it's a scheme. That's why it erases all partitions on the drive.
Recommended swap was 2x the RAM on the old days of Linux 2.4... Don't know why this persists on some pages. Now a days, you'll only need the same as RAM, specially if you want to hibernate, for Linux does it into the swap partition. I don't recommend hibernation on dual boot systems, you may corrupt your Windows partition if you write in it from Linux. Windows keep the information of the file systems on the hibernation file, it doesn't re-read everything. Unless you run heavy applications or hibernate, with 6 GB of RAM, there's no need for swap. I have 16 GB and a fast SSD, it's faster to cold boot than to resume an hibernation, so I have no swap ever.
KaOS uses xfs as default instead of ext4, but feel free to choose as you wish, I've even installed on BtrFS without problem.
I'd rather use an USB pen drive than a SD card: it's easy to find very fast ones at reasonable prices, and you may even take it with you to use on other machines. Anything starting at 16 GB capacity is more than enough (can be done with 8, but with a high probability of getting full). Personnal information may be kept on the Windows partition.
KaOS has a cutting edge approach, very different from LTS releases. OS X is a very nice system, you just can't bend it to your will as can be done on Linux. Most of the time, it's more about how much you are willing to spend on the hardware.
Hope it helps. Regards from São Paulo!