Would the word "you" be written Tù or Tu?
There is no grave accent (`) in Spanish. So you can write "tú" for "you", or "tu" which means "your". Although there is no need to use "tú" or the other pronouns as much as in English because you can guess the subject of the sentence by the verb.
What is the rule for using Yo hablo Español or Yo habla Español?
You'd say "yo hablo español" because "habla" is used for the third person (él habla). If you find hard to conjugate verbs, imagine it's like third person "s" in English (I do, you do, he doES), but we have a different ending for each person
. Well it's a little harder, but you'll get used to it.