Can I keep working on "do X Y times" achievements by replaying missions?

As a general rule, a reference should be reliable/authoritative for what it says. So whether or not a reference is acceptable depends on what claim you are using it to support, and whether the source has the authority/evidence to make that claim.

A news website would not be an authoritative reference for technical information. For example, this would not be OK:

• "With 5G wireless technology, a web page will load in a millisecond [1]." The writer of the article is not an expert in 5G technology, and there is no evidence in the article to support this claim. Instead, to make this claim, you should cite a reliable technical reference that offers evidence.

However, a news website might be a useful reference for other things where it is an authoritative reference. For example:

• "Media portrayals of 5G have not necessarily been realistic - for example, Adweek has claimed that with 5G technology, web pages will load in a millisecond [1], but the IMT 2020 technical requirements for 5G [2] specify at least 1 millisecond of latency for just a small subset of the network path." Note that Adweek is not a good source for the claim that web pages will load in a millisecond - the writer of the article is not an expert on 5G! - but it is an acceptable source for how 5G technology has been portrayed in the media.
• "Bob Metcalfe, who is called the 'father of Ethernet', said that the developers of the Ethernet standard believed voice and video over Ethernet would be impossible [3]." Here, Bob Metcalfe is a reliable source as to what the developers of the Ethernet standard thought at the time, and an interview with him is authoritative for this.

Jettison from the App Store for $1.99 has helped me with this.

It's a menubar application that helps in 2 ways: You can click and eject all drives (the only problem is that you can't say something like "Only eject drives connected to the Thunderbolt Display"); you can also select an option to eject all drives when putting the computer to sleep (so if you are disconnecting your computer to go somewhere, you can put it to sleep, wait a moment, then unplug everything).

That being said, I now use Launchbar to accomplish this. I just activate Launchbar and select "Eject All Ejectable Volumes". I'm willing to bet other app launchers (Quicksilver, Alfred) can do this just as easily.