Joseph, actually almost all produce in Israel has had terumot and maaserot separated as having a certificate widens the consumer base. For the same reason even HaShomer HaTzair kibbutzim have kosher guest houses.
Akuperma,
1. Time crowned him “King Bibi”.
3a. Apparently it was economically feasible as some people had them (e.g. Tabi, Rabban Gamliel’s slave). One could not “work them to death” as they kept Shabbat, yom Tov and Chol haMoed.
b. A mamzer is allowed to be with his shifcha kenanit – and Rabbi Tarfon even advises this (Kiddushin 69a).