Advice/Help on finding rims for 2000 Mountaineer

[ajv0982]

I know alot about cars, but have never had to fix anything related to tires so I've got a few questions I hope yalls expertise can help me with. I really want to stick the 18" rims off the Mercury Maurader onto my Mountaineer, will they fit? If not, I'd like to keep a semi-stock look to my rims, so does anybody know if there is any Mercury or Ford Racing rims out there that would fit that are 17" or larger. And let's just say I do go aftermarket does anybody know the widest I can go tire wise on the back and front to not have rubbing issues (like 255, 275s, what size)? Also and I don't really understand all the termnology and spacing, and lug size and all that stuff they list on websites when you're looking at rims. Thank you for anyone who took the 15 minutes to read this and 30 minutes it probably took for a response.