No, Minecraft mods do not cost money, and are completely free of charge. I have never ran across any mods that require you to pay. In the related links below is a rather extensive list of mods, in the official forum for Minecraft. If you really enjoy the mods, in the thread, some mod makers provide a donate button. OptiFine specifically will award you for donating by giving you an OptiFine cape, visible only to other OptiFine users!
It does. It should work with a lot of other mods as well.
Check MinecraftForums or the MinecraftWiki. They'll tell you. I recommend TMI and Optifine to start.
Lots of mods do not need forge, big ones such as: OptiFine Too many items and Better Sprint (all i know of)
Optifine is another but not too many texture packs and mods are compatible with it. It just depends on what you use.
Optifine is only required for HD texture packs; it is not required nor necessary if you don't use/have any installed to your texture packs folder. ModLoader/Forge is needed for some mods, but not all; it's best to consult the mod's topic and read the requirements to be sure whether or not the mod needs either mod loader installed.
I think I know what you mean. "Looking further" is actually part of a mod for Minecraft, OptiFine. you can press Ctrl on a PC to zoom in or "look further" at distant objects. The whole description about OptiFine is on the Minecraft Forums if you would like to check it out. For a brief summary, OptiFine basically just supports your Minecraft and makes it run better. Personally, I am not into Minecraft mods too much, so you should probably go read about OptiFine on the Minecraft Forums if you want an accurate description.
Donate to optifine, or buy minecon tickets. (I have a optifine one)
Yes you can download them together however these two have some bad history together and when installing certain mods with them both installed may cause error, just a heads up.
There exist mods, the most popular being which allow this sort of thing. OptiFine allows zooming in by pressing the Control key. The closest thing in vanilla Minecraft is to use a bow and arrow, and aim the bow toward where you want to look, and to fire it when you are done looking. You loose an arrow in the process, however.
No.
Optifine is completely free to download. If you need help installing it look up youtube videos how to install it