Reddit mentions of 10 Rollos Kodak Ultra Max GC 135 – 36 – Película de 35 mm ISO 400 de impresión de color (PACK OF 10)

Looks like an original FM to me. First thing you'll want to do is replace the light seals. You can get a kit on eBay and there are lots of tutorials on youtube. It's easy and you'll want to do it otherwise your shots will be ruined by light leaking in. I've used that eBay kit many times for different cameras, it's great.

The 135/3.5 is a good lens for distant landscapes and head shots, but you'll want a wide-angle for a lot of the shots in Yellowstone. Having been there many times, I would recommend picking up a wide angle like a 24, 28, or 35. If you can spare $250 or so, I'd get a Nikon 24/2.8 AI or AI-S for $150 and a Nikon 50/1.8 AI or AI-S for $100. In my trips there, I usually alternate between 24mm (very wide) and a telephoto (I use a zoom lens, a 75-150 f/3.5 Nikon Series E, which you can get for about $60). Anyway, a wide angle combined with your 135, should cover a huge variety of shots. If you need something super cheap, consider a Nikon 28/3.5 AI or AI-S, which you can usually pick up for under $100. You could also tack on a Nikon Series E 50/1.8 which you can get for about $60 if you want a cheaper 50mm. (For low-light, handheld photography, it's good to have at least one lens with a low f/number (large max aperture) like a 50/1.8, which lets in 4x as much light as a f/3.5 lens at it's widest aperture. But if you have to get one lens, get a 24, 28, or 35. If you can get two, add on the 50mm too.)

As far as the strap, I'm not sure the original FM came with one, and if it did, it was probably just a basic black one. My favorite Nikon strap is the wider, burgundy Nikon AN-6W / also in yellow: AN-6Y, but also check out a Nikon AN-DC3 (red, black, brown, or gray) for a narrower strap. There are also tons of aftermarket straps out there, such as the classic Domke Gripper. If you want something cheap, call a local camera store and see if they have used straps, which they usually sell for $5 or less.

You might also consider getting a small tripod for Yellowstone, which you can usually find very inexpensively on your local Craigslist. Nothing mandatory, but it will open up the ability to shoot long shutter speed images without blur, such as night sky shots, landscapes around the time of sunset or sunrise (usually the best time to shoot landscape; get up early or stay up late, I can't emphasize this enough, don't waste the golden/blue lighting hours of the morning and evening sleeping or hanging around camp! One trip I got up at dawn almost every day, went out shooting/hiking, came back to camp and took a nap, then went out again in the evening for more shooting. Definitely recommend this if your companions will tolerate it.)

My favorite film for Yellowstone is Ultramax 400, which is a great general purpose color film that gives that classic film look with punchy, saturated colors. It's cheap at $4/roll if you buy 10 rolls of 36 exposures (amazon), which is great, cause you'll want to shoot a lot when you're there. If money is no object and you don't mind shooting a slower 100-speed film, then Ektar would be a great choice for saturated colors but with less grain than Ultramax. If you want to go really retro, and really cheap, Kodak Colorplus is a 1980s-era emulsion with saturated colors. It's quite grainy, but then some people love that.

For general film tutorials read your camera's manual. There are some great articles on the wiki, and on this site's beginner's guide to film photography. Make sure before you go, you have a good grasp of how shutter speed and aperture settings affect your image, how to focus and control depth of field, and generally how to use your camera. There are lots of good overviews of the FM on youtube. The more you read, and the more your practice shooting between now and then, the better off you'll be. There's tons and tons of information online. Also, read some articles on good spots to take pictures at Yellowstone. Sometimes they're a bit off the beaten path.

Regarding drug stores, they can be OK placed to get film developed and prints made but only if they return your negatives. Some still do, many don't. Ideally, find a lab nearby or mail them out.

Walmart by me has the 3 packs of kodak gold for $12.

You can sometimes score cheap rolls of film on amazon if you're willing to buy in bulk; eg: https://www.amazon.ca/Rolls-Kodak-Ultra-135-36-Color/dp/B013KE71P4/ref=sr_1_68?s=electronics&ie=UTF8&qid=1485202016&sr=1-68&keywords=film