Starting with just 5 stitches you'll have to use either Magic Loop, two circs, or DPNs .
As for joining, the easiest join I know is to cast on one extra stitch. Slip one stitch from the right needle to the left, then slip the second stitch on the left needle over the first one (the one you slipped from the right) and off the needle (just like a bind off). It's now joined.
Another join method is to slip one from right needle to left (also would have to cast on one extra) and then just knit two together which also creates a join.
I prefer the bind off technique but both work.