Yes, carpets should be replaced after a house fire or significant smoke damage, even if they appear undamaged. Smoke, soot, particulates, and chemicals can penetrate deep into the carpet fibers and padding, making complete removal a complicated and time-consuming process. If water was used to extinguish the fire, it can also soak through the carpet and padding, creating a risk of mold and mildew growth. Due to these challenges and potential health risks, replacing the carpet is the safest and most effective solution.

You may be able to use super glue in a pinch to fix your carpet, but expect the repair to last only a short time. Super glue isn't designed for carpet, so over time, it'll break down, and the carpet piece will move out of place. For the best results, go to the store and grab a bottle of carpet seam glue. 

You can get away with stretching the carpet with some remaining items of furniture, so long as you have ready access to the parts of the carpet that require maintenance and you are not stretching through the furniture, as this leads to tears and fraying. Try to remove at least 50% of the furniture if you can’t remove it all.

Yes, carpeted stairs are generally considered safer than stairs with hard surfaces like wood, vinyl, or tile. Carpet provides more traction, which helps reduce the chances of slips and falls, and its cushioning can lessen the severity of an injury if a fall does occur. Hard surfaces often lack the friction needed for a secure tread and can be quite slippery.

However, it's worth noting that some carpets can also be slick, particularly if they are brand new, dirty, or made from certain materials. If any stair surface feels too slippery, traction treads can be added to most materials to increase grip and improve safety.