Scrub of the rust with steel wool or a brillo pad or something. Don't use soap!!! Don't ever trust a "pre-seasoned" skillet. It's just not adequate. So, to re-season (or to season a new pan), melt a fat in the dutch over. You can either use a high smoke point oil (ie canola, safflower, peanut, etc) or use an animal fat. The ideal would be to cook some bacon in the pan. After the bacon is removed, spread the bacon grease all over the inside of the dutch oven. Heat your oven to about 500 degrees (F) and put a cookie sheet on the bottom rack. Then turn your dutch oven upside down on the top rack. Let it hang out in there for about an hour, then turn off the heat. Leave it in there until it's relatively cool. Wipe any excess grease with a towel, but don't wash it. Seasoned!
Jeanette- I bought the 5 qt. and have made bread as the perfect size for his recipe. The pan is quite heavy and the larger size you are asking about would be to big. I think... Happy baking, his bread is the best!
Depending how roast was cut. We usually cook about 3 lb cuts of meat, but I think you could get a 5 lb roast in there. If you have more than 4 in your family you may want to go with the bigger one, but we have gotten by with the 5 qt for many years, and raised 5 kids. Start with the 5 qt. won't be as heavy, easier to handle. If you find you want a bigger one get the 7qt. Or, do like we did, add another 5qt. We have two because of having a dozen or so folks at some family functions and they all love roast beef.
I use mine (the solid-handled version) primarily for frying chicken and deep-frying, with stews and chilis running a close second. For use on a stovetop plus sometimes the oven, the solid handles are easier to grab with a hotpad, and make transfers from burner to burner, or burner to oven. If I was using a firepit for the cooking, the bail would probably be easier, but for indoor cooking, the solid one's easier for me to move. Hope that helps!
You certainly can, but this is a heavy piece of cookware so you probably don't want to slam it down, and you should lift it to move it rather than slide it around to avoid scratching your cooking surface.