Maybe someone else can help ya with the Aluminum part of your question, BUT, I can help you with Folding Wooden Attic Steps.
Century makes a nice set. It's about $30+ more than Husky's. Husky has much bigger springs than Century's. Century's is better made, IMO. Husky's hinge-welding stinks. If you try to bend them back in place, you'll break the weld. (Sometimes, the hinges get stressed from use and they bend inwards. The springs have a lot of tension on them.)
My best to ya and hope this helps.
PS: The rough opening should be fine. Century is sold at lumber yards, for sure. I've seen the Husky in the Home Centers. You can try the various Home Centers like Lowe's and Home Depot but you may end up going to a Lumber Yard because the aforementioned stores don't carry Century.