When allowed to vote for two do you have to vote the required number?

Only your association can answer this.

Most of the time though, the votes you didn’t use are treated like you’re voting for non of the above. This actually does matter in most elections since you have to get a majority (50%+1) and not a plurality (more than anyone else) to win.

Sometimes, but not always. Sometimes you may cast both votes for one candidate, but not always. Find out how your HOA docs stipulate voting.