In regards to a case, I use the "Powerbox" made by Husqvarna. It's basically a square box for the saw's powerhead, and has with a a plastic scabbard for your bar (which sticks out of the box). It fits lots of different saws, and has room inside for some extras. I keep a bottle each of of 2-cycle oil, bar oil, and gas stabilizer in it. I also throw in a scrench (screwdriver/wrench), a chip brush, and a dry rag. It makes a great seat when it's break time in the woods, and you can stack stuff on it easily in the truck (due to its flat top). They're not cheap, but I think they're worth it.
As per saws, I've had a Stihl 026-Pro for about 12 years and have been very pleased with it. It's dependable, and isn't so heavy that your arms feel like noodles after a day of cutting. My 650 spends a lot of time sitting in the truck.
Most people that I see struggling with their chainsaw are running a chain that is way too dull. Don't spend hundreds of dollars on a saw and then skimp on the chains (I buy Stihl chains). I buy extra chains so I always have a sharp one on the saw and at least one in the saw box. I also keep my chains in "Tupperware" style sealable containers. They don't get rusty from sitting, and they don't snag anything in the sawbox. I don't file my chains - I send them out to be ground when they need sharpening. Cutting roots can dull a chain very fast.
- Marty