You can use almost any vegetable that you like in this dish. Cauliflower, broccoli, zucchini, etc. all will work great! Just remember that some vegetables take longer to cook. If you use broccoli, you may want to wait and add it when you add the sausage so that it doesn't get burnt.
You can use any oil that you prefer. I usually add about a Tablespoon of oil per pound of veggies. You want them to have a nice coat of oil so that they roast well and get that nice crispy roasted taste!
You can also add whatever spices you like to this dish! It is very easy to customize for your preferences!