A MovieUna película: Batman!

You could write the exclamation marks, but then you must also add the quotation marks to make clear that they're not part of the title.

Hola mi, mejor amiga mía.

This is more of a content thing: does it make sense to greet her again? You've already done it with "Querida Sasha:".
In vocatives like this one (which have to be separated with comma), it's more stylistic to put the possessive at the end: "Amigo mío", "Querida mía" and so on.

Pues “Una película: <Batman>”??? Correcto ??

Espero que tus vacaciones soean buenas,(,) y estés haciendo toda des las actividades de las que hablábamos antes de salirirnos.

Unlike in other romance languages, the verb "esperar" in Spanish is formed with the subjunctive mood; in fact, you did it correctly in the second subordinate clause.
It is not strange to see "hablar" being used as a transitive verb, being the direct object the subject of the conversation (mostly with pronouns, e.g. "Lo hablamos ayer."). However, this use is colloquial, so I changed it.
Instead of "hablábamos", you could also use "hablamos" depending on how you wanna portray the action.

Pues, to say ´best friend´ I could say amiga mía en lugar de mejor amiga ¿ Or did you mean it should have been: Querida Sasha: Amiga mía...

Me sSiento comoque no he hecho nada.

If you use it as a pronominal verb, the meaning changes.

¿Hizo calor, no?

Where? Where your friend is or where you are?

Queé fantástico.

There's a difference between the stressed "qué" and the unstressed "que".

Había olvidado coómo de/cuán bueno es el cine es.

Same thing with "cómo"/"como".

I wanted to say Ï hope you are doing all the activities that we spoke of before we left¨ So correcto: ...y estés haciendo todas las actividades de las que hablábamos antes de irnos And, in this context, does ´las´ Clarify the subject of the past discussion as the activities ?

Pero, loa vi con mi hermana mayor, y,(,) ahora, ella(,) no puede esperardejar de hablandor sobre motos y cómo son frescosde/cuán estupendas son .

"Ahora" can be written as a digression (with commas) or not (without), depends on your style.
You have traduced "cool" with the meaning of 'cold'. Other alternatives would be "guay" (colloq.) or "increíble".

Fran.

A dot is not used here.

¡Ya, por favor,; visiítarme pronto!

Remember (!) the imperative.

No entiendo, quería decir ¨I feel like I have done nothing¨, so pronominal verb (sentir) changes not reflexive if its meaning is accompanied by a metaphor or technique or hyperbole? Siento -> no he hecho nada.

I wanted to say it has been hot, no?

I'm not sure what you mean. Could you elaborate?

Kind of, "de las que" is what introduces the relative clause. "Que" is the main particle and, in this case, it goes with "de" because that's the preposition that the verb "hablar" uses ("Hablé de todos mis problemas, pero no me escuchó."). When that preposition is "a", "con", "de", "en" or "por", you can actually write it without the "las" part ("de que"). However, it is very common to include it, because, this way, it cannot be mistaken for something else.

De bueno = of good, if I am going to use como + adjective, must I always do cómo + de + adjective?

Gracias, pues ; Cool (colloquial) = guay Cool (formal) = increíble. And (conjugated poder) dejar de + infinitive = (to not/permit) action

You have to differentiate between "sentir" being used with the meaning of 'I think, my opinion is' and the meaning of 'I am experiencing a physical sensation'. Your sentence means (as I understand it) "I think I haven't done anything" → "Siento que no he hecho nada". If you write "me siento", then it's "Me siento como si no hubiese hecho nada", which means "I feel as if I had done nothing", i.e. I don't feel tired at all, I'm not experiencing the physical sensation of tiredness. An example with this meaning: "Me siento como si no hubiese hecho nada, podría correr diez kilómetros más sin problema.". Does this clarification help?

That's correct, my question is: where has it been hot? If you're friend is on her holidays, I guess she traveled somewhere, right? If this is the case, there are two different locations in your text: the one where you are and the one where your friend is. I'm only saying that it is not clear which one of the two you're refering two. This is just a question of content, not grammar.

I wouldn't raise "increíble" to the category of formal, it's just standard. "Dejar" is one of those verbs that has a trillion meanings, so I wouldn't categorise it so fast. Here it's "she cannot stop doing it", not with the meaning of actual permision/necessity; it could also be written as "she cannot stop doing it because of her enthusiasm", so strictly speaking, it means she doesn't wanna stop doing it.

Ok so imperative + attached object you stress the second last vowel. Thnx.

If you're talking about the degree/level of the adjective and want to use "cómo", you must include "de". But that happens in this context, I don't know what you mean by "always". As I've said previously, don't try to translate from one language to the other, "cómo de" is an inseparable structure, so it's not "of good". Consider this, I see the sentence "It happened because of the rain." and I say, so it is "because of" = "porque de"? Does this make sense?

The stress in the imperative doesn't change. This means that adding enclitics ("me, se, lo") can change the accent (capitalised to emphasise): viSIta = visit; if you add the "me" (visit me) → "viSÍtame", now the accent is necessary because it's the third to last syllable. Another example: esCRIbe = write; esCRÍbeme = write to me; esCRÍbenoslo = write it to us.

So the correct phrasing would be Una película: «Batman»

Ok I understand count back <- 3 vowels from the end then add accent/stress. But if its both a direct+Indirect attached you do not count the indirect thank you