Flip adapter is generally for close-up lenses. If you want to shoot macro subjects with the 16-50mm kit lens, you need to attach a close-up lens (also called wet diopter) to the front of your port - this will allow you to focus closer than with bare lens, but will also limit how far you're able to focus, giving you a window of sorts in which you can focus on subjects. The stronger the diopter, the smaller and closer to your camera this window is, allowing you to shoot progressively smaller subjects, but restricting you from shooting larger ones. Since screwing/unscrewing those diopters takes time, a flip adapter is useful to quickly adapt your camera to your current needs. If you're shooting stills, you don't really need a red filter as RAW + postprocessing is easier. If you're shooting video in natural light, it can be useful, as a6300 white balance range is limited.
A vacuum system saves you from most leaks in two ways. First, you use it to remove some air from the housing some time before the dive, then monitor the internal pressure - if it starts rising, this means air is getting in somewhere, and submerging with the housing in this state is unsafe; you have to fix the seals so that this stops happening. Second, it pre-loads the o-ring seals on the surface, making them less susceptible to breaking the seal by getting bumped (say, in a cluttered rinse tank). However, the fixed-port housing that you're looking (the translucent purple one) at doesn't have a vacuum system port - if you want to use a vacuum system to prevent another flood, you need the Salted Line housing (
short macro port bundle if you want to use 16-50mm with wet lenses). Also, the SeaFrogs VPS-100 vacuum system is a very poor design, as it cannot be used underwater - its seals fail after 70-80 dives or so (I've had three die on me that way), at which point it starts leaking. Vivid Housings Leak Sentinel has a version that works with SeaFrogs housings; it's more expensive, but very very worth it. I haven't seen it advertised for sale anywhere, but if you write to
info@vividhousings.com, you can order one directly from the manufacturer.
