Semantics: sense and denotation, intension and extension?

Question

I'm sorting out my notes on sense and denotation, but I'm confused. When comparing sense and denotation, which of the following statements is correct?

1. Denotation points at things (set of all cats). Sense is the idea/concept a word conveys (cat... small furry domestic animal with four legs, meows...)

2. Denotation can point to either the set of all things in the real world (extension), or to the set of all things in all possible worlds (intension).

3. Denotation points at the set of all things in the real world (extension.) Sense is our concepts about what the word conveys for the set of all things in all possible worlds (intension.)

4. Denotation only deals with the real world.
Denotation does not ever deal with the set of things in all possible worlds.

5. Sense never deals with sets.
We never talk about sense applying to the set of all things in all possible worlds.

6. Both sense and denotation CAN deal with possible worlds.

Thank you! If you were able to answer my question, I'd appreciate it if you'd look at the other questions I'm asking today!
(There's no good category for Semantics or even Linguistics...)

I also have this written down:

7. Extension- the real world. This is denotation, and the denoted set changes when the real world changes. Sense changes according to the real world too. ("the president" denotes GW Bush now, but will denote someone else in the future. The set of all cats only contains the cats that currently exist in the real world.)

Intension- all possible worlds. Also denotation; denotes things in both the real world and imaginary worlds (all possible worlds), and the set of denoted things can change. Sense does not change despite the changes in the denoted sets.

8. Truth Condition = circumstances necessary for sentence to be true in all possible worlds = intension

Truth Value = whether the sentence is true in the real world = extension

Answer 1

1) Prima facie true.
2) If you're a realist about possibilia, then true. Otherwise the actual world is the only one with any denotation.
3) Yup.
4) Yah.
5) No.
6) It entirely depends on your ontology. No, unless you are a realist about possibilia.

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Sense drops out if there are no uninformative identities.
Denotation doesn't do any work if sentences are semantically atomic. Meaning is so meaningless.