Il C'était un cadeau de Noël.

It's pretty tricky to explain, but when there is a very descriptive sentence, with an emphasis on what's being said about the subject, the most natural pronoun is "ce"

Il me tient chaud, malheureusement, il est en orange fluo.

"en" is used to describe materials something is made of
It's sometimes used with colors, but in very particular contexts. For instance if you're trying on a dress in a shop, you can ask "est-ce que vous avez la même EN bleue ?" (= do you have the same dress, but in blue, basically, do you have the blue version)

Mon fils en a reçu un bleu.

Je veux'ai voulu les échanger.

Even if you still want to change them, the verb would be in a past tense to connect it with the past moment when you tried and your offer was turned down

Mais, il a refusé catégoriquement.

There is no comma after a coordinating conjunction starting a sentence

Elles C'étaient des cadeaux aussi.

"ce" for the same reason as above
Indefinite quantity of something countable = des => des cadeaux

J'aie les offertai proposées a mon fis, en plus du bonnet fluo.

"offrir" would mean you successfully gave them
"proposer" means you just suggested that/made the offer
In this sense, the English "offer" is a partial false friend compared to its English cognate

Subject + (in)direct object pronoun(s) + auxiliary => tu M'AS vu, nous LEUR AVONS parlé, je LES AI proposées...

The past participle agrees with the direct object ("les = les chaussettes") since it stands before the "avoir" auxiliary (règle du COD antéposé) => je les ai proposéES

Il m'a dit, "Hrépondu/dit : « hors de question »."

Direct speech is ideally introduced by a colon
French quotation marks => « »
Only the first word of entire quotes is capitalized