The bloomers are started separately, with the front and back crotch panel worked back and forth, then joined to work upwards in the round, using a circular needle. There is only one seam for sewing, which is the gusset seam.
If you prefer to work front and back separately, and then side-seam, cast on 1 extra stitch on each side, and work this as a garter stitch edging stitch throughout. This will give a 1-stitch edge for seaming.

The honeycomb stitch is written, not charted.

DK Yarn: 50g 1 (2, 2) balls
Needles: 4.00mm & 3.00mm circular
Cable needle