Water vapor inside lens mark ll how do I remove it?

Use a hair dryer from the outside or leave the headlights on to dry out the moisture. Check the lens assembly for any cracks allowing water in.

The filters attach to the back of the lens. Remove the lens from the camera. Look where the lens fits onto the camera. Inside you'll see the screw threads that match those on the filters.

1. Carefully clean your binoculars by firstly removing any dirt or dust from the main body and straps using a soft microfibre cloth. Avoid the lenses at this point using any form of cloth on the lenses before removing all dirt and dust particles first could destroy them.

1. Gently remove all traces of grit, dirt or dust particles from the lenses using a soft lens brush or canned air specifically designed for the purpose.

1. Waterproof binoculars can be rinsed gently under a tap but be sure to use on lightly running water, avoid high pressure water as it could damage your binoculars.

1. Gently remove any remaining marks using lens cleaning tools such as a lens pen or lens cleaning fluid and lens tissue. Do not be tempted to use kitchen towel or anything else lying around that is slightly rough and may scratch the surface of the lens, only use a lens pen, lens tissue or a lens cloth. Gently wipe the lens using a circular motion working from the centre of the lens to the outer edge. NEVER apply lens cleaning fluid directly onto the glass (always apply to the cloth) and always ensure that the lens cleaning fluid you are using is recommended for the type of lens coatings that have been applied to your binoculars (Do not use general household glass cleaning products or products designed to clean computer screens or glasses. Such products could destroy the lens coatings of your binoculars if used).

You can use some absorbents to dry off the residual moisture but the marks might remain due to stain of the water. So try to use a hair dryer to warm the camera very carefully. Once there is no trace of water, but the marks remain on the lens , then it is important to remove the lens assembly after dismantling the camera so as to clean the lens using proper lens cleaner.
Attempt only if technically inclined and with proper tools.

If your softener is working properly, you should never get any salt in your water. The salt is used only to reactivate the ionic media in your softener cartridge, and during the backflush cycle, all that salt is removed, down to PPM (Parts Per Million) levels.
In any case, even if you used salt water in your vaporizer, it would not increase the amount of steam that it produces. Salt water has a higher boiling point than fresh water. You would also notice salt buildup inside the tank as the water level goes down.
The Vicks Vaporizer works by using only heat to produce steam- the hotter it gets, the more steam it makes. The only practical way to get too much steam outside of a malfunction that causes your heating element to get abnormally hot would be if you live at a very high altitude where water boils at a lower temperature.
High humidity in your home will make it appear as if your vaporizer is making too much steam since the surrounding air will be less capable of absorbing it.
A slightly "off topic" note- if you chose the Vicks Vaporizer/humidifier and have children, you have made a wise decision. Because it produces water vapor by heating instead of ultrasonics, contaminants and minerals (such as salt, iron, calcium, etc.) remain in the tank and will not enter the vapor stream.

Nope. Not really a fixable one.

something has stopped up the toilet or sewer line beneath the toilet

Unfortunately, the lens on the 6500fd is not a removable lens, and if the water is on the inside of the glass, you will want to send it in for a good cleaning.

The problem with electronics getting a bath is that although it works now, after drying, the water that was inside will promote corrosion of the internal workings of the camera over time. I would definitely send the camera to Fuji or to a qualified service center and have them give it a good cleaning to slow or prevent the decay of the insides of the camera.

I hope this helps.

This cannot be addressed except by a qualified artificer, and the cost would be prohibitive. Replace the camera, and be more careful in future.