Another one to add is that Japanese boys names often end -rō (-郎, "nth son")... including the very plainly named 一郎 (Ichirō, "first son"), 二郎 (Jirō, "second son"), 三郎 (Saburō, "third son"), 四郎 (Shirō "fourth son"), 五郎 (Gorō, "fifth son"), 六郎 (Rokurō, "sixth son"), 七郎 (Shichirō "seventh son"), 八郎 (Hachirō, "eighth son") and 九郎 (Kurō, "ninth son")
I don't know about Ancient Romans, but I do know a few Italian men with numbered names. In particular a Decimo (tenth), who was indeed the tenth (and I wouldn't swear the last).
I'm not sure. 4 and death just sound the same, it's more a superstition to avoid saying those numbers, like Westerners thinking 13 is unlucky. It doesn't extend to all words beginning with or containing "shi"
Also, shiro (城 castle or 白 white) is not the same as the name Shirō (e.g. 四郎 "fourth son", 志郎 "determined son"?, 史郎 "historical son"?)