2. In the code for your teleport (change map) event have one page do nothing then add another page that has a precondition that the party holds a certain item, on the later page have the teleport event that takes the party to the next location.
3. You could have a switch turn on at the same time the player recieves the item. Then in the code for that battle have a conditional statement that if the switch is off ( hence the player hasn't recieved the item) the monster is given a condition that makes him evade all attacks. Just make sure they can't get rid of the item or that something turns off the switch if they do.
4. Yes, use the "enter hero name" function located in the second page of code command options.
5. All you need is a simple paint program like MS Paint, there are size and color restrictions though.
6. You could place in the battle code for each battle something like if Character X HP is between 0 and 25 percent inflict exhausted condition on Character X.
BTW I'm assuming your using RM2K3, if not I think most of this is still right. Best of luck with your RPG.