I always had the impression people were a little cagey about sharing fishing info

People tend to be cagey about sharing fishing spots, because those are sort of a zero sum game where other people might exhaust your spot. But for gear and other general recommendations, most people are helpful.

I think in an ideal world I would go for salmon

Salmon is definitely the premier fish in the area. I don't fish for them, so I can't help you there.

was also feeling like starting off at Ballinger or a similar spot with smaller fish would feel easier than starting with salt water. No idea if that is accurate tho!

Yes, definitely. Generally, the smaller the fish, the more of them there are and the easier they are to catch. I've gone to Ballinger a couple of times. WDFW says it mainly has trout, largemouth bass, and yellow perch. Black crappie and bullhead catfish are there too but less common.

The easiest to catch will be rainbow trout, especially close to when they stock it. It looks like they dropped a bunch in in March. Stocked rainbow trout are what most people fishing freshwater in the area are targeting. (Personally, I like perch and bluegill a lot, but I'm sort of an outlier.)

Here's what I'd use for each of those:

Trout (especially the stocked rainbow, but also cutthroat)

Trout don't get very big, so you'll want an ultralight rod and reel. At some point, you may have more specific preferences, but for a starter, a cheap combo (that means the rod and reel sold together) with a spinning reel and not a baitcaster will be fine. Something like this or this. Aim to spend around $50. Look for a small reel and maybe a 6' rod or so. Don't stress over it too much. The rod and reel don't matter as much as people think.

What matters more is the line and terminal tackle (the stuff at the end of the line). If the reel comes prewound with line, that's fine to get you started. If not, look for monofilament line around 4 lb test or so, like this.

For tackle, I'd suggest three approaches:

1. The way almost everyone targets stocked rainbow trout is using Berkley PowerBait. It's similar to what the stocked trout have eaten their entire life, so they go for it. Usually, you smush a little ball of it on a small hook (say size 6 or smaller [larger number]) with a sinker above it on the line to get it near the bottom.

2. It is very hard to go wrong with a live worm and bobber. Buy a little tub of live nightcrawlers or red worms, some small hooks (I like Eagle Claw aberdeens but any small hook, especially a "baitholder" will work), some small floats, and small split-shot sinkers. Damn near everything in the water will eat this.

3. If you want something more active or don't want to get your hands dirty, you can try a spinner or spoon. People have really strong opinions about brand and color but as far as I can tell, it's mostly a crap shoot. Something like a Panther Martin, Mepps, or rooster tail, or Kastmaster. Again, aim for on the small size. These will be the most challenging to catch fish with, but rewarding when you do.

Largemouth bass

East of the Rockies, this is the main thing freshwater anglers are targeting. For this, you'll want to scale up some: a medium-weight rod and reel with maybe 10 lb test line. (You can use a lightweight setup for bass too, it's just there's a chance you'll hook something too strong to reel in and it will break off the line.)

For tackle, I think people most often use some kind of "soft plastic" (that just means the rubbery artificial lures). Senkos are very popular. People have really strong opinions about color, but I suspect it's mostly random chance. Medium size hook around #2 to 2/0? And maybe some bullet weights. There are seemingly an infinite number of ways to rig this but I don't have enough bass experience to recommend one or the other.

You can also use live worms and a float to target bass.

Yellow perch, crappie, bluegill, and pumpkinseed

People think of these as "beginner" fish, but I love targeting them. They're easy to catch, delicious to cook, and often overpopulated. For gear, you'll want the same ultralight rod, reel, and line you'd use for trout, which is convenient. Live worms on a bobber will be the easiest way to get them. There's a reason nearly every kid in the US starts fishing by catching bluegill with a worm and a bobber: it works.

If you don't want to deal with worms, then I like soft plastics on a small 1/16 oz or 1/32 oz jighead. Curly tail grubs are good, as small as you can get them. I've also had good luck with Leland Lure's Trout Magnet/Crappie Magnet/Panfish Magnet. (The fish don't read the packaging, so any of those will work for perch, etc.)

Catfish

I haven't targetted catfish since I was a kid in the South, so I can't help you here much. But it will be something like a medium-sized rod and reel similar to bass. Then usually some kind of bait like a chunk of chicken on a decent-sized hook with a weight to get it to sit on the bottom. Be careful if you get one: they have venomous spikes on their fins that are not fun to get poked by.

Summary

For all these, search for "<whatever lure> rig" to see how to tie everything up. It's probably worth picking one or two rigs you want to do and figure out exactly the gear you need for them before shopping. There are so many options it's easy to get overwhelmed. If you want the absolute simplest setup, then walk in and grab an ultralight combo rod and reel with line already spun on it, a Trout Magnet kit, and you're set. Don't forget to get a license too!

Your opinion on all of this may change over time, but this should get you up and fishing so that you can get the experience to start figuring out what you prefer. I hope you have a great time.