A few questions:

1. How do/will user-defined types and inheritance work?
2. Can object elements switch type dynamically?
3. Can I programmatically overwrite script elements? For instance, if this is declared:

<object "someObject">
    <take type="script">
        msg ("Test: " + myfunction("one", "two"))
    </take>
</object>

...can the take script be changed using something like this?:

<someElement type = "script">
    object.take = anotherObject.take
</someElement>

3. What kind of functionality will come with the list type? (Or, what kind of operations will exist for lists?)
4. Can an element be assigned an object reference?

<object "someObject">
    <myTarget = someOtherObject>
    <someMethod type = "script">
        this.myTarget.doSomething
    </someMethod>
</object>

<object "someOtherObject">
    <doSomething type = "script">
        ...
    </doSomething>
</object>

5. Is there are built-in null type? (Can I set values to nil somehow?)

1. You can define types and then you can specify that objects include a particular type, just as you can in Quest 4. It's a bit more efficient in Quest 5 though as the types aren't physically copied over to the object - looking at an attribute on an object will "look through" to its inherited types.

2. I've not implemented this yet, though it will be necessary for objects created at run-time.

3a. Yes, an expression can return a script, so you can do:

myobject.take = anotherobject.take

and you can set the script directly:

myobject.take => msg ("New take script")

3b. At the moment you can create lists of strings, objects or exits. You'll be able to add or remove items, concatenate lists, and check if a list contains a particular item - all the standard stuff really.

4. Yes an attribute can be a reference to another object. For example myobject.parent refers to the parent object, so you can write:

msg ("The beer is in " + beer.parent.name)

5. Yes you can use null.