Upgrading PA? Mine is mostly junk.

[SnowCal]

I'm not a PA guru so I'm not really sure what I should be doing here. We don't use it outside practice in the chicken coop as our venues all provide a PA, but we're going to need our own for a house party with a couple hundred heads in attendance.

I've got an old 8-channel Peavey mixer. Perfectly functional but not very fancy. I think it might be a Unity Series 1000. And then a pretty old and not very high wattage Peavey amp. Plenty of mics. Not sure if it's supposed to be a guitar or PA amp. Bad attempt at 'it can do both'? It doesn't seem very colored. And then I've got two fridges. They're 1x18s but have dual horns and the displacement of an 8x10 and are really well built. Multiple jacks on the back and something about full range near one and crossovers and subs near the other.

I also have an A&H Zed10Fx that I'm guessing is the mixer I should use live but I typically keep it at home to play around with. And some geriatric BGW pa amp that is rated for less than 200w with weird output jacks on the back.

Not a huge budget here, but I'm trying to figure out where to improve. Do I get a better amp? Maybe some more mid-range cabs and explore the world of crossovers, as I think these beastly 1x18s might supposed to be subs. Sticks? A compressor?

Sorry for the very scattered post. I'm pretty clueless here.

[SnowCal]

Did some research and figured out that the Peavey amp is a 150w bass amp and older than I am. Go figure. Solid state tech so sterile I use it as a pa amp.

[tbirdsp]

No replies because your post is so "scattered". Need more information.
How many mic channels do you need?
What all is going to be run through the PA?
18's with dual horns??? What brand/model?
What about monitors?
What's your budget?
How often do you plan on using this stuff to gig out?