i would recommend downloading the gamestudio AUM magazines found here: http://www.3dgamestudio.com/
read through them, download the demos, tweak the code, same goes for here: http://au.conitec.net/
there are alot of demos and such in the above links, play with them and try to learn the few basics

AVOID USING THE TEMPLATES if you really want to make a game with your own custom feel

2- liteC is the newer scripting language used with gamestudio A7, c-script is the older language for A6 and lower, liteC gives alot more functionality to the coder and in my opinion is simpler to understand and work with

3- i dont know what you mean exactly and i never was good at telling what a skill is, took me a while to understand them perfectly, but basically they are values that you cant attach to entities, for example health, you could have 10 players with their skill1 being their HEALTH and you could decrease each players health without affecting the others...

4- if you wanna do multiplayer games, i really would advise that you atleast get you basic game idea running in single player mode first, which is what i did, the knowledge will be valuable when you take on a multiplayer project, i wont give the link for the multiplayer system you could try using, simply because i really think you should try singleplayer first but theres the built in gamestudio multiplayer engine[tricky to work with] and theres Anet[requires you to code a few systems, interpolation and such]

5- not exactly sure what you want here but am sure someone else will answer

am also sure someone else will clear up any mistakes i mau have made above, am too lazy/busy/tired/hungry/unmotivated to read it over so i apologize for typos

welcome to the community, may you become a great designer and not rampage the forum looking for posts to criticize lol

-dark inferno-