are subwoofer cables, 7.1 analog cables, video component, and outlaw pca interconnect cables all interchangable?
do they all do the same thing?

The Outlaw PCA's are analog audio cables: that means they can be used for any analog audio connection (2.0 analog from source to receiver, 7.1 analog from source to receiver, pre-amp outputs to power amps, or output to a subwoofer). Component video, composite video, and coaxial digital all require a 75ohm connector - which you don't necessarily get with an analog audio cable (because it isn't required). For those three applications, a cable such as Outlaw's PSC is recommended. If you have a cable that was made for use with component video, composite video, and coaxial digital, it can be used for analog audio. I would not recommend doing the opposite, however.

That is, unless you use M series Monster cables. As I gradually moved away from analog audio equipment over the years, I retired my (pricey) M series audio interconnects to the parts box. Later, when I'd misplaced a coax I needed, on a hunch I looked at the mess of L/R audio cables, and they are, indeed, 75 ohm coax construction.

This may be true of other expensive cables, if you can see there is an insulator around the center pin (plastic ring, vs. all metal connection), it's probably coaxial construction.

Basically all line level audio cables are of coaxial construction, 75 ohms or not. There is no way to tell by just looking at a cable what it's characteristic impedance is unless it is clearly marked on the jacket as a 75 ohm type (such as RG59). Don't assume that just because a cable is "coaxial", that it has a particular impedance. RG-174 for instance is coaxial, but it is 50 ohms.

if an audio cable fits into the component video port of my outlaw 990 then must it be a 75ohm connector and then is that audio cable ok to replace a "video" cable?

No - the RCA connector is the same regardless.

gonk, then how do tell just by looking at a cable if it has a 75ohm connector?

There is no way you can tell if an RCA connector is 75 ohms unless it is marked that way. In fact, the only true 75 ohm RCAs that I'm aware of that can be easily purchased are made by Canare, and they are clearly marketed as having a 75 ohm characteristic impedance.

There is a way to tell of a BNC connector is a true 75 ohm, but no easy way to describe the difference because it is subtle.

Honestly though, there is little degredation that will likely take place if just the connector is not a true 75 ohms and the rest of the cable is.

The Eichmann Bullet RCA plugs sound the best! They are also perfect for your own digital Coax cables when you do not use BNC!