No. In free worlds, members items cannot be used in any way, nor can they be sold. Your only options are to keep the items, or to drop them in order to get rid of them until you are able to sell them via the Grand Exchange.
You shouldn't need to worry however, since members items occupy members' bank spaces and do not affect your free bank spaces.
No you cannot. Member Items become completely worthless and untradable on a Free to Play World. For you to Trade/sell or buy a members item you must become a member of Runescape.
Wield (in a member's world, and keep wielding while in f2p. You cannot start wielding it in f2p), drop (some might have special effects, eg.: ectophial, god capes), examine (every member's item has the same examine phrase in f2p) or deposit in the bank (provided you have enough space for it. Some items cannot be deposited, though, like the lamps from A Small Favour quest). The use option is useless, since the member's items are unusable in f2p.
There are, nevertheless, a few items obtained in member's worlds which can be used in f2p, like Maple Logs.
Non-Members: 2 Members: 6
You don't need any specific world. You can sell most stuff at the Grand Exchange, which is shared among all worlds.
Yes, non-member items can be used on members servers.
Members can sometimes get trimmed or gold-trimmed items from treasure trails. Non-members can buy them on the Grand Exchange.
The only Guthix items in RuneScape f2p is the Guthix rune armour. The only way you could get these items for free are via gift, drop party, or player killing.
Rune Items like scimitar, you can get these from those level 83 cockroach soldiers.
Yes, it is both Non-Members and Members.
Get some resource (for example, do some mining, or kill cows), then sell it at the Grand Exchange.
you cant
No.
78 types of items for non-members, 516 for members. Each of these "slots" can hold up to about 2 billion of a single type of item.
The sacred clay sword is a members only reward from the newest members mini game, Stealing Creation. Non members cannot use these items.