In Early Modern English, ye was the nominative(subject) plural of you. The whole conjugation looks like this: Singular Subject: Thou Singular Object: Thee Plural Subject : Ye Plural Object: You In Standard English, "you," has replaced all other forms. In the past you would say: "Did ye go to the store?" In Standard American English, you would say: "Did you (all) go to the store?" Note: Many people think that ye = the, but this is incorrect! However, you will sometimes see it used that way. For example, a store might be named: Ye Olde Gift Shoppe (The Old Gift Shop). While it is good to know these things because you will sometimes see them, it is best not to use them in conversation because, here in America at least, they sound funny. We only use these forms when we are joking (or playing Dungeons and Dragons or something).

"I prefer" is simple present tense. When you say "I prefer" you are saying "I always like," because sentences in the simple present are habitual, or always true. I would prefer (I'd prefer) is a conditional, and this means that your preference relies on something else. I'd prefer is often used with "rather than" or "over" or "to" Example: I prefer coffee over tea I prefer coffee to tea I prefer coffee rather than tea Since prefer ALWAYS takes a gerund (-ing verb), your first sentence is correct.

opt for = decide on / choose I opted for coffee instead of tea with breakfast. I always opt for plain coffee. Would you opt for candy over vegetables? Should I opt for a fixed rate mortgage instead of a variable rate mortgage?

In fancy terms, this modification of voicing is called Rendaku. http://en.wikipedia.org/wiki/Rendaku