>>635
I'll try and answer your questions (and hopefully I'm right on this)
for
Icecream (wo) spoon (de) eat.
It's correct, particles are always related to the word before it, a way I think of how it works is: Wo = object of verb, de = by way of, or just by. (de can have many more meanings)
So let's look at this sentence, 'Icecream is the object (i) eat by spoon.'
This helps me make sense of it.
koko ni iru
makes more sense, you are here
koko de iru
Here's where de has another meaning which you mentioned, the problem here is that iru is a verb but it is not considered an action verb. I'm not sure what constitutes a difference between verb and an action verb, but just living is a pretty shitty verb compared to something as playing. Now that I think of it, non-action verbs are probably passive verbs, as living would be passive.
へ is indeed read as "eh" when it is read as a particle (otherwise it's "heh") just like the particle は (ha and wa)
As for ageru/kudasai/kureru..
Ageru is the Japanese word for "to give" seen from the speaker's point of view. You must use this verb when you are giving something or doing something for someone else.
I (wa) you (ni) object (wo) give
I give you object
kureru is also a verb meaning "to give" but unlike ageru, it is from the receiver's point of view. You must use this verb when someone else is giving something or doing something for you (effectively the opposite of ageru).
you (wa) I (ni) object (wo) give
You give me object
In anime you might hear something like 「教えてあげる」 oshiete ageru, meaning something like, "I'll teach you"
If you reverse this, 「教えてくれる」 oshiete kureru, it means something like, "Will you teach me?"
Now you said kure and not kureru, kure is the imperative form making it a demand, so 「教えてくれ」 is something like, "Teach me!"
Kureru can be considered more impolite than kudsai, especially if kureru doesn't have masu on it; however, they really are two different things.
I may be wrong but I don't think sageru is really related to any of this. Sageru means to lower, and just that I think. Ageru can mean to raise, or to give, two different things.
I'd say the polite imperative is more polite than just the regular masu form, I think the difference is probably the same in English; Can you please? Or will you please?
To say stuff more polite, you make yourself more polite and more humble, look here for more examples, there's a bit too much for me to cover in this post
http://www.guidetojapanese.org/honorhum.html
I suggest you look at
http://www.guidetojapanese.org/favor.html as this guy explains the stuff better than I do, he also has a section on kudasai
sorry if I rambled through the whole thing, hopefully I didn't say anything wrong/misleading.