I would like to identify the pattern of the purse in the image below, and want to know how to begin the chain number of the stitch. Is it a double crochet or single crochet? What type of yarn do I use for this?
I'm about 99% sure that isn't crochet, Tunisian or otherwise, but knitting. There are quite a few "diagonal" knitting stitch patterns out there, and this looks to be one of them, made with knit and slipped stitches. Look up "diagonal basketweave knitting pattern," which seems close. It's finished with crochet slip stitches all along the opening, and of course, the flower. A pattern for a similar flower would be:
Ch 6, sl st. in first ch to form ring. ch 4, tr 3. ch 4, sl st in to loop rep. italicized portion 5 more times for a total of 6 "petals"
This flower is very similar, although in the picture it does look as if maybe that one was done by making single crochets in a magic ring and THEN making the petals by going in to the sc stitches. And also they seem to only have 5 petals, and something I can't make out to attach it to the purse. Maybe 10 sc in a loose magic ring or a ring of chains, going in to every other one on the second round.
This looks like tunisian crochet.
Here's an article about how to get started with it https://www.purlsoho.com/create/tunisian-crochet-basics/. Cotton seems to be the most common type of yarn for handbags. I'd recommend a cotton cord yarn for extra durability and to show off the stitch texture.