Hi LauraAna!
Even in Spanish we make mistakes all the time, some people don't care, others don't know. But when we talk about communication workers, I think we should be careful. They just make me jump out of my skin when I hear them saying things like: "Si podría lo haría" (something like "I'd make it if I'd can) when the correct verbal tense is "Si pudiera o pudiese lo haría" (I'd make it If I could) , and belive me it's a very frequent mistake in Spanish... but it's wrong... too many conditionals
Do you get my point?
As regards the use of YO it might be a cultural thing where you put the subjet. In general, it's correct to drop the subject, you can use it or not, somthing you can't do in English. In Spanish you can say "yo me fui", but in a real situation you will hear "me fui". The subject is "tacit"
Hope it helps!