In Italian, you can use "piccolo" and "grande" as synonyms for "giovane" and "vecchio". It's colloquial and a bit childish though. The most common sentence that you can hear this is "cosa vuoi fare da grande?", which is used to ask a child what he wants to do as a grownup.
I put Lei è giovane e sono vecchio and was wrong. Aug.2017
I was under the impession that either io sono or sono were correct but Italians will just use sono because it is easier.
In Spanish you could say yo soy but soy is sufficient.
Sometimes Duolingo falsely marks correct responses wrong. If that happens again, flag it and select "My answer should have been accepted" (after double-checking you didn't make another error that would invalidate it).
The rule in Italian for "e" vs "ed" ("and") is very much like the rule in English for "a" vs "an". If the next word starts with a consonant sound, you use "e". If the next word starts with a vowel sound, you use "ed".