Yes — the listing names hemp and organic cotton, both plant fibers. The visible slub texture in the close-up photos is characteristic of natural yarns rather than synthetics.
It is loose and boxy by design, with drop shoulders. Based on the product details, your usual size keeps the intended relaxed drape — size down only if you prefer a closer fit.
Natural fibers can shrink with heat, so wash cold and lay flat to dry. Dried this way the knit relaxes smooth, and most owners of slub knits skip the iron entirely.
Based on the product photos, the slub knit reads opaque in normal light. It is lightweight, so a skin-tone layer underneath is an option if you prefer extra coverage.
No — the stripes are yarn-dyed and knitted into the fabric, so they stay crisp wash after wash instead of cracking or peeling like a print.