I don't want to attempt cutting the squash whole. I also thought that roasting it first might bring out some of it's flavor.
Roasting it first will certainly add flavor. I like to roast it cut open and the seeds removed
Do you have recommendations for roasting time/temp?
Roast at 400-425 for 20-30 min. depending on the size. Place the squash cut-side down. The squash is done when it's fork tender and golden brown
Roast the whole squash,seeds included. Scoop out the seeds as you are making the soup. Then ,rinse and dry them and sauté' them in a little olive oil, sprinkle with sea salt and black pepper and use as a garnish for the soup.
Also, if your squash is a good-sized one (over 2 pounds), it probably will benefit from 40 minutes in the oven. Lightly oil the baking sheet, as the sweet juices that flow from the squash are likely to caramelize quickly in the high heat. Also, consider using the skin of the roasted squash, minus any really black bits, in a stock for the soup. It will add a lot to the flavor of the soup. ;o)