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.
Lots of mods do not need forge, big ones such as: OptiFine Too many items and Better Sprint (all i know of)
No.
Yes, optifine.net
Donate to optifine, or buy minecon tickets. (I have a optifine one)
Check MinecraftForums or the MinecraftWiki. They'll tell you. I recommend TMI and Optifine to start.
you download the optifine file, and drag it all into the minecraft.jar in the bin folder in the .minecraft folder, making sure that you delete the META-INF file, otherwise it wont work, and then when you log on to minecraft, go into video settings and play around with it, and change the controls for them in the controls.
yes as of now
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.
Minecraft forge is a free program.
MC Forge will always use its latest version. Therefore, backup your Minecraft and install your second Forge. Forge will use its latest version.
use a 64-bit java to run minecraft. Or install optifine to reduce lag
No but is you get Optifine you can