Durable: very - no failures (other than self inflicted failures such as backing into something or bolts coming loose).

Long do they last? At least 4 years (that's all the time I have on them.

Special Hardware? No - nuts and bolts - use nylocks and don't overtighten.

Carpet lasts a good while. I don't know how they attach it but I suspect they may do it in the mold.

Lubricant on the carpet - yes, occasionally.