Do languages that use non-Latin alphabets (Asian, Cyrillic, Greek, Hebrew) have upper and lower case letters?
Greek has upper and lower case. From mathematics/physics you may have seen e.g. the ones for sigma (Σ, σ). Cyrillic also has them; most are the same shape just bigger/smaller (Л, л) but there are some that differ (А, а).
I don’t think most Asian scripts have letter cases. Javanese does have upper case but only for a small subset of letters and they are generally not used anymore.
What about serif or sans-serif?
Cyrillic and Greek, yes. There are also equivalents to serif typefaces in Chinese, Japanese, and Korean.
How do they show emphasis?
On the Web, boldface (but not italics) is very commonly used across various writing systems. Obviously no all caps for those without capital letters.
Greek has upper and lower case. From mathematics/physics you may have seen e.g. the ones for sigma (Σ, σ). Cyrillic also has them; most are the same shape just bigger/smaller (Л, л) but there are some that differ (А, а).
I don’t think most Asian scripts have letter cases. Javanese does have upper case but only for a small subset of letters and they are generally not used anymore.
Cyrillic and Greek, yes. There are also equivalents to serif typefaces in Chinese, Japanese, and Korean.
On the Web, boldface (but not italics) is very commonly used across various writing systems. Obviously no all caps for those without capital letters.