What's the Name of That Book??? discussion

Goodreads, I was watching a star talk episode clip about interstellar. The important part is NDGT said something about going to a planet close to a blackhole.
That reminded me of a sci-fi space opera book series I read many years ago. The parts I can remember are how humans are fairly new to space travel. And something to do with a bar or agency where people are paid good money to use some sort of pods that actually belong to whole other species that was thought to have gone into hiding or simply disappeared somehow to avoid being killed off from a even more advanced, brutal, hostile species. From what I remember humans didn't actually understand how to use the pods all that well, but many coordinates were marked as bad because they'd take the pilot to dangerous location so certain death. One human male adult (?) tried his luck and the description said "the unmistakable maw of blackhole". I think this same book involved a murder plot on a space ship, and a who-dunit.
I want to say book that takes place in the same series much latter actually involves one of the mysterious species of aliens who were very friendly to humans. So much so that at one point in this books series two kids: one human one of the friendly ___'s (I can't remember the name :( ) but something about they were gaunt and thin, and kind of humanlike, and the author noted that they complained that human math was 'so positional' .
I think a human child and a child of family of ____'s went to a library or something? something to do with using a recording device that somehow captured a message from a very brutal old species that everyone thought had died off a long time ago. Somehow this childs recording thing when she took it to someone to figure out what the noise was, that recording accidentally got mixed up for whole other one. And the kids recording was braudcast all across the planet somehow releasing some of the hostile species, as well as alerting the ___'s that were still in hiding to come out and help keep earth from being taken over. I think the ___'s ships were so advanced they were able to hide using blackholes somehow.

I had thought these memory snippets might have been from the uplift war series. But I just can't get google to show me enough details for anything to ring a bell.
Anyone have some other ideas what the book series I'm trying to remember might be?

Long time since I read it, but the pods thing reminded me of Gateway, from Pohl’s Heechee books. I never read any more, so no idea about the rest of your memories. Good luck!

It definitely does not sound like Brin’s Uplift series.
The Uplift War

Sue wrote: "Long time since I read it, but the pods thing reminded me of Gateway, from Pohl’s Heechee books. I never read any more, so no idea about the rest of your memories. Good luck!"
Aha! After skimming some teasers on amazon I think that was the series!

SOLVED!

Glad you found book, Gork.

Gateway (book 1 of the Heechee Saga) by Frederik Pohl