This is just the part of the course for learning hiragana though, so it wouldn't make sense to jump directly into kanji just yet.
It is labeled as Hiragana, but this is actually numbers, so Kanji is appropriate since Hiragana isn't used for numbers.
"san" in anglo which follows a personal noun of a familiar person vs. "kun" which males use when addressing males of the same age or younger. "sama" follows the noun or the person if the person is older or has a higher degree of age or status in the society. I do recall from my Japanese study YEARS ago!
Except those are never used by themselves. In English you would say, "Hey, mister!" and everyone would understand you. You could say 「おいさん!」but everyone would think you were yelling at Mr. Oi. If you were to write the honorifics properly, it would be -san, -chan, -kun, and -sama because they are suffixes not words. In Japanese it's ~ instead (~さん).
Google is a better place to ask because no one knows what hardware nor software you are using.
三 us never pronounced mittsu/みっつ. Using いくつ, the generic counter, 三 is pronounced み, and っつ is appended, making the spelling 三つ. I guess officially as the いくつ counter, 三 is pronounced みっ with つ appended, but having that っ included in the pronunciation can be confusing because it is mostly silent. At least, it confused me a bit at first.