Mis amigos y yo queremos coleccionar postales de cada ciudad.

Both are possible:

• Mis amigos y yo queremos coleccionar postales de cada ciudad.
• Nosotros queremos coleccionar postales de cada ciudad.

In Spanish, “mis amigos y yo” is often used to spell out who “we” are, especially in conversation or when first introducing the topic.

“Nosotros” is shorter and more neutral. Once it’s clear who “we” refers to, Spanish speakers may then just use nosotros or even drop it and say simply:

• Queremos coleccionar postales de cada ciudad.

Yes. In Spanish, when you say “X y yo”, the group always includes “I”, so grammatically the subject is “we” (nosotros).

So:

• Mis amigos y yo → nosotros → queremos (1st person plural)
  NOT quieren (3rd person plural, “they want”).

Compare:

• Mis amigos quieren… → they want
• Mis amigos y yo queremos… → we want

Grammatically, “yo y mis amigos” is not wrong, but it sounds less natural and is generally avoided in careful speech.

In Spanish, people usually list themselves last:

• Mis amigos y yo (preferred)
• Mi familia y yo
• Juan, Marta y yo

Using “yo y…” is more likely to sound childish or egocentric, just like overusing “Me and my friends” in English.

In Spanish, “querer + infinitive” doesn’t take a preposition:

• Queremos coleccionar postales. = We want to collect postcards.
• Quiero aprender español.
• Quieren viajar a España.

You never say “querer a + infinitive”. The pattern is simply:
querer + [infinitive verb]

Coleccionar specifically means “to collect (as a hobby)”, usually in an organized way:

• coleccionar postales, sellos, monedas, figuras, etc.

Other verbs:

• recoger = to pick up / gather (physically picking something up):
  
  • Recogimos las postales del suelo. (We picked the postcards up from the floor.)
• juntar = to gather / put together:
  
  • Juntamos muchas postales. (We gathered many postcards.)

For a hobby collection, “coleccionar” is the most natural and precise verb.

Coleccionar is standard and common in Spain as well as in Latin America.
A Spaniard would very naturally say:

• De pequeño, me gustaba coleccionar cromos.
• Nos encanta coleccionar postales.

So this verb is perfectly appropriate for Spain Spanish.

Yes:

• una postal = a postcard (feminine, singular)
• dos postales = two postcards (feminine, plural)

The noun is “la postal”. Many nouns in -al are masculine (el animal, el hospital), but “la postal” is an exception: it’s feminine.

So the sentence correctly uses:

• postales (feminine plural) after coleccionar.

You could, but it’s not necessary and sounds more formal or technical.

• tarjeta postal = postcard (literally “postal card”)

• In everyday Spanish, people usually just say “postal”:

  • Voy a enviarte una postal desde Madrid.

So “coleccionar postales” is the most natural everyday way to say “collect postcards”.

The prepositions express different ideas:

• de cada ciudad = from each city (origin)
  • We want postcards from every city.
• en cada ciudad = in each city (location)
  • Would sound more like “We want to collect postcards in each city,” which is a bit odd; you usually collect postcards from places, not literally in them.

So “de cada ciudad” is the natural choice to express postcards that come from each city.

• Queremos coleccionar postales = We want to collect postcards.

  • Focus on intention or plan: this is something you want to do.

• Nos gusta coleccionar postales = We like collecting postcards.

  • Focus on enjoyment: this is something you enjoy as a hobby.

So they express different ideas: want vs like, just as in English.

Yes, Spanish allows subjects after the verb:

• Mis amigos y yo queremos coleccionar postales.
• Queremos coleccionar postales mis amigos y yo.

Both are grammatically correct.

However, the most common and neutral order in everyday speech here is to put the subject first:

• Mis amigos y yo queremos coleccionar postales de cada ciudad.

The correct spelling is “coleccionar” with two c’s:

• co-lec-cio-nar → coleccionar

“Colecionar” (with one c) is a spelling mistake and is not accepted in standard Spanish.