Spanish language Q&A Forum

Newbie here: I’ve always been told that Spanish accent is usually on the penultimate vowel, and only the exceptions need an explicit tilde mark. 

However, there are conjugations, like actuéis where the accent mark is on the penultimate vowel. I would have thought that the accent wasn’t needed anymore. Any place I could go to with a fuller explanation?

Thanks.

hi room and experts

Please clarify why 'tener  + participio cases' must have agreement in gender and number with the noun acting as a direct object,  whereas  this rule does not apply in  'haber + participio cases'

For example  -  Tienes ya pensada la estrategia para convencer a Inés? - (show agreement)

He pintado dos habitaciones. (does not show agreement)

When you are talking to a young person and mention another person who is older (and vice versa, speaking to an older person and mention a younger person), but refer to the people as you, which verb choice should you use, vosotros or ustedes?  

Examples: 

John (older person) and you (child) are going to the store tomorrow. How to translate You (both) are going to the store tomorrow (speaking to a child when the older person is not present)?

You (older person) and Maria (child) are going to the store tomorrow. How to translate You (both) are going to the store tomorrow (speaking to the older person when the child is not present)? 

Also, does it matter which form is used (vosotros or ustedes) whether or not both people are present (both older person and child)?

Is anyone else just chipping away at the Spanish lessons here hoping that one day they will understand enough to have the courage to talk to someone in Spanish?  I'm level B1 in the lessons, but probably A2 when it comes to writing, A1 when it comes to listening and A0 when it comes to converations! 
I fully understand I won't ever be fluent unless I talk with Spanish people, but I'm level C2 at making up reasons why today just isn't the day.