Good questions. Never any harm in asking for help. It gives us poor sad old folks a chance to make ourselves useful
1. Guilds vary a lot. Some are "family" guilds and are there mostly for mutual support, helping you find groups and just giving you a feeling of not being alone in the Big Empty. They may include greater or lesser degrees of roleplay. Others are more oriented towards raiding and may be less supportive and more demanding. The best way to find out is to visit your server boards and look at which guilds are recruiting, see what their charters are like and try and find one that fits your kind of person. Then seek out opportunities to group with their members and see what they are like in-game.
2. Min is 3 people. they are winnable with 3. If you started one and 2 left then you would be soloing but you would be unlikely to win or get much exp. The key aspect of LDoN seems to be the ability to either prevent (Pacify etc) or control (Mezz etc) multiple pulls. Unless you could do this solo you would likely get stomped. If you were extremely well geared then it might be viable.
3. You cannot auto switch but by doing what you have and putting the inventory slot on a hotbutton you can also put your Primary and Secondary on hotbuttons (or use a Custom UI that does this for you) this way you can pick the weapon from inventory and exchange it with the one in Primary/Secondary without breaking combat or having to open the inventory window.
4. Skill rises will be fewer on light blues and non-existent on greens. They are not however noticeably faster on reds than on blues in my experience. I believe "Mob" derives from "mobile" meaning any moving object in the game world.
5. Well according to SoE "There is no such thing as a camp". however common usage and courtesy designates anything that is a fixed spawn as a camp. Orcs in EC for example have fixed locations where they spawn and this is a recognised camp. Bears spawn randomly all over the place (watch where you tread) and could not be called a "camp".
There is no real limit to the amount of time you can camp something provided you are actually there and killing the mobs. If you go off to sell, go afk, or otherwise stop working the camp then be prepared to lose it. Be prepared also for people to have strange definitions of what they define your camp as. If the mobs are giving you exp and you want to camp them then it doesn't really matter if you are one person or a full group. if you are alone and farming greens for some reason (faction, tradeskills etc) then I personally would give way to an exp group who wanted the spot. Opinions may differ on this one.
Also if you are not able to kill all the mobs before they respawn then be prepared to share the camp. It will probably be safer for both of you.
