So I'm looking at upgrading some parts on my Araya. The most important parts, imho, are going to be my brakes, and derailleurs.

Current stock brakes:



Shifter (what's the little metal bar below do? I've never seen anything like it before):



Current rear derailleur:


I wanted to switch this over to avid cantis, but without the proper setup on the frame I'd be stuck dealing with a hack/hangar option. Is there a better choice?

I am a bike snob so nashbar, tek and promax ain't gonna cut it.

On the rear der., couldn't I go to a Campy record 9-speed and keep the shifters i currently have?

Look at dual pivot side-pulls or good quality Centerpulls for the brakes , for example,
Velo Orange: https://www.velo-orange.com/grco610cncbr.html

You have a freewheel hub on the back , don't get too ambitious with the bike you have.

Cantilevers are a Brazed on brake fitting, Go forth and buy a new bike ,
with the kind of parts you want.

A cyclo-cross bike frame is made around having cantilever brakes on it ,
Campag group would put that at $3K.

The little metal piece below your shifters flips out and locks the front wheel. It keeps the bike from rolling and helps prevent the handlebars from turning when parking the bike and leaning it up against the wall. We used to sell them from a cardboard display stand in the 80's.

Let me know if you don't want it.