Yes if you consider picking things up that people drop or leave behind and selling it.
You don't. You have to buy it.
Killing goblins
No, there are no 'cheats' for RuneScape.
Go to the hairdresser in Falador, he does it for free.
Karjama for free players
maybe or maybe not i expect not
Mining runes.
the only ways to get rune rmor for free is to make it, get it in the party room drops, kill a monster, or clue scrolls for members.
yes they can i play and am a lvl 123
You can play for free, but if you have a membership, the payment is monthly.
Kill lots of lessers demons and greater demons, they drop rune armor.
Rune-scape and DragonFable are extremely addictive.