What can I expect having a salpingo-oophorectomy?

Depends. Depends on how it's done. Done laparoscopically (through small incisions) in your abdomen, recovery will be easier. If you're premenopausal (still getting a period), ovarian removal will put you into immediate menopause, likely causing common symptoms like hot flashes, insomnia, emotional lability, vaginal dryness, etc. You'll want to talk with your obgyn about how to manage this.
Surgery. A salpingo-oophorectomy by itself will not change your periods unless both are taken. If both are taken, you will enter menopause. The amount of surgical pain is related to the type of surgery, open or laparoscopy.