Make it as big or small as you want; it’s build up with a repeat of stitches and rows. Or use fingering yarn to change size.
The gauge mentioned is in the fantasy-stitch of the shawl.
A circular needle is easier as you obtain a lot of stitches on the end!
Is convenient for beginners as long as you can knit, purl, increase and decrease as explained in the pattern instructions.
(if explanation of fantasy stitch seems confusing, read this: knit two next stitches together through the back loops + knit first of those two stitches through the front loop. Then drop off those two stitches from left needle.)