Depends if you're p2p or f2p.
Addy,Rune,Dragon is obtained either through drops or I believe clues with exception of dragon.
2. You can buy runes from Aubury, Mage Guild, and Ali (but some sort of req to unlock him I forget). I just buy my runes all the time, especially when you can enter Mage Guild - the stock is 1,000 runes.
Side note: If you are training Magic or Range, it's recommended to do so in EOC, because then you only use runes for each auto-attack (not the abilities). For Legacy, it seems you use runes per each hit.
3. No, but there should be guides lurking around. I actually learned alot from being in a ironman/woman clan though from all the chatter... could guest in one and ask and I'm sure people can help too.