I am a fan of Isaac Asimov. I definitely suggest the books The End of Eternity and Nightfall.

Difficult to say. If you keep in mind, that he wrote the sequels 30 years or so later and acknowledge that one's views change over such a period, then go ahead. If you, however, expect the same flavor as the trilogy, then I wouldn't recommend reading foundation's edge and foundation and earth. And although these are meant as an introduction to the men behind time, that one makes no reference to the foundation trilogy. So it's fine to just read the end of eternity on its own.

I can only comment on the sequels so far since I haven’t gotten to the prequels, but I’d say if you are open to a bit of a change in pace then it’s definitely worth it. But it’s definitely a bit different, it was written like 30 years later as someone else mentioned. So definitely worth taking that into consideration.