Mandarin tones don't sound the same all the time. Just because you mastered how to pronounce tones individually doesn't mean you can say them right strung in a sentence. In a sentence, the tones often "blend" into each other. The highness, lowness, and length of tones vary according to how they're used in the sentence, and there is stress on certain syllables over others. Many tones are "omitted," resulting in the "soft tone." As mentioned, the length of a syllable can vary, and a protracted syllable at the end of a sentence can change tones at the end. And Mandarin doesn't need "ma" at the end of a sentence to indicate question.

1st tone syllables: higher = question, lower (or slightly dropping at the end) = statement
2nd tone syllables: exaggerated rise = question, smaller rise = statement
3rd tone syllables (fall-rise): ends in high rise = question, ends in fall or low rise = statement
4th tone syllables: higher, smaller drop = question, lower and larger drop = statement
For example, the syllable "hao3" (good) used alone sounds like a question when it ends in "rising" (good?) and sounds like a statement when it ends in falling. The third tone is not always completed, and in a sentence often sounds like a low-tone instead of a "dipping" tone.

As for conveying emotion, Mandarin can do that, but it's hard to describe. I hope I didn't scare anyone from trying to learn Mandarin. The emotion-conveying is pretty obvious after you practice listening and doesn't require additional studying-time!