When do you use "Jinde" and when "Jinam"?
It is the position vs. direction distinction. Something like English here vs. hither and there vs. thither. Jinde is a position (elsewhere) and jinam is a direction (like elsewhither, which is extremely rare).
Although people do say "somewhere else", more often people say "elsewhere".
And indeed, that is accepted too.
"Ta nová ulice vede nikam jinam." Was correct, but with a typo. How do i know if i should use "nikam jinam" or just "jinam"?
does not anywhere else - nevede (nIkam) jinam
leads somewhere else - vede (nĚkam) jinam
Both někam and nikam are optional here.
Oh I see. First I mistakenly used nIkam instead of nĚkam, which was the typo.
Are there instances when jinam requires the use of nikam/někam?
I do not think so.