Yes, it is generally safe to have a fire pit on a deck, but you must adhere to building codes and take several safety precautions. For both built-in and freestanding models, you must use a heat-resistant barrier, such as a fire pit pad or heat shield, between the pit and the deck. Additionally, consider the weight of the fire pit and ensure your deck can structurally support it, reinforcing it if necessary. The fire pit must also be positioned a safe distance from your house, particularly from materials like vinyl siding, to prevent heat damage.

While you can use various materials like sand or even just soil, gravel is widely considered the best option to put under a deck. It provides excellent drainage and is resistant to water, fire, and pests. Gravel also helps anchor the soil to prevent erosion during heavy rain and acts as a built-in weed blocker, reducing regular upkeep. Furthermore, it is simple to spread, available in various textures and tones, and adds a polished look that complements any deck design.

Ultimately, overapplication of stain can compromise the deck's appearance, durability, and longevity. It may result in an uneven finish, with excess stain pooling, dripping, or drying into thick patches. It can also obscure the wood's natural grain and texture, detracting from the desired aesthetic. Moreover, excessive staining may not fully penetrate the wood, leading to poor adhesion and premature wear. Additionally, thick layers of stain are prone to peeling, cracking, and blistering as they struggle to bond with the surface. 

Choosing whether your deck should be lighter or darker than your house is a matter of personal preference, as there is no right or wrong answer. However, considering the pros and cons of each can help guide your decision. Darker colors are often chosen because they show less dirt, footprints, and marks from daily wear, making them easier to keep clean. On the other hand, lighter deck colors tend to stay cooler in the summer. From a design perspective, using a deck color that contrasts with your home's exterior can help make the deck a more defined and distinct feature. Consulting color theory can also make the process of choosing a complementary house and deck color combination easier.