The correct answers are If I were a local, I wouldn't wear this shiny silver suit., If I was a local, I wouldn't wear this shiny silver suit., and I wish I knew how to ride a horse.

To talk about unreal or hypothetical situations in the present, we use the second conditional (If + past simple, would + infinitive). For the verb "to be", both the traditional subjunctive "were" and the informal "was" are grammatically accepted in modern English. To express a desire to change a present situation, we use "wish" + past simple (e.g., "I wish I knew").