Ideally, a gate should be able to swing both in and out. However, if it can only open in one direction, it is generally best for it to swing inward. This is often the safest option, especially for deck gates near steps, as you'll want the gate to swing away from the stairs. An inward swing also prevents the gate from opening into a public space, like a sidewalk, and can be more convenient when carrying heavy items like a wheelbarrow into a garden.

There are exceptions, however. The layout of your property may require a different approach. For example, if your property is on a slope, the gate may not be able to swing inward. You should also ensure the gate can open fully without colliding with any objects or blocking access to other areas. For a backyard garden gate where public access isn't a concern, the direction it swings is largely a matter of personal preference. Finally, always check your local building codes, as they may have specific requirements for which way a gate must swing.

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. 

Composite decking may never warp, or it may warp quickly. Several factors can influence the rate of warping, including the material's quality, installation method, and installation location. Generally speaking, high-quality materials that have been installed properly are drastically less prone to warping.

It is definitely worth sanding a deck to ensure the wood absorbs new stain. Sanding a deck removes the outer layers of aging wood, allowing the stain to penetrate. It also gives a fresh look to the entire surface as part of the deck refinishing process. Without sanding, your stain or sealant is less likely to absorb into the wood. While sanding a deck is a time-intensive project, the rewards are noticeable and long-lasting.