This is a good thread showing all the little problems that pops up. Nice build.
Frizzen's idea of holes that look planned is a good one, but just in case you want to feel better about a swiss cheese look, here's my frame:
https://imgur.com/ljK1lre
About the servo connectors. If they're black, they're probably standard / universal / JR servo connectors. I don't think they have another name. They're basically shaved down versions of what's commonly known as 1x3 size dupont 2.54mm connectors. Same internal metal things, same general shape, but the Duponts are squared off. A kit containing various sizes is nice to have. I get a lot of use out of 1x1, 1x2 and 1x3 size.