Congrats on deciding to ride, motorcycling is awesome! For the kind of riding you're doing, pic related (DR-Z 400) is an awesome choice. It gets old pretty fast on the freeway, but for anything under 65 mph or so it's brilliant. Great handling, fun engine, comfy riding position, and completely bulletproof mechanicals. If you plan on doing a mix of street and dirt riding, the DR-Z 400 is great. If you're looking at street riding only, look at the DR-Z 400SM. It's a supermoto version of the DR-Z 400 (basically smaller wheels for quicker handling, among a few other things). Craigslist is the way to go for sure, don't go to a dealer unless you want a new bike. DR-Zs tend to be pretty damn reliable, but bring along a mechanically knowledgeable friend when you're looking to buy a used bike, just in case. Look out for anything with title issues or non-running bikes. Title issues are a massive pain in the ass, and whenever a seller says a bike will run with "a little work" assume they mean a full engine swap.
The hoodie looks good, but possibly look into getting something mesh, ideally with CE level 1 elbow and shoulder protection. something like:
http://www.revzilla.com/motorcycle/alpinestars-t-gp-plus-air-jacket
or maybe
http://www.revzilla.com/product/joe-rocket-phoenix-50-jacket
As long as it's mesh and CE level 1, you're good. CE level 2 is better, but much, much pricier. The hoodie you have linked is good, but it probably won't breathe as well as something with more mesh.
Back protector is definitely a must, at least for me. Make sure it's the kind that straps directly to your back (instead of being a jacket insert) and make sure it's CE level 2 (most back protectors are).
The neck protector thing looks cool, but honestly, neck injuries are pretty rare in my experience. It might be cool, but I imagine it'll get really hot and really sweaty, really fast. Neck braces are super important for technical off-roading, but neck protection for road usage never really struck me as completely necessary.
I'd highly, HIGHLY advise you get some mesh pants with knee protection (optional hip protection is also a plus). When you're moving, mesh pants breathe incredibly well, but keep your legs safe from road rash (which FUCKING SUCKS, believe me). Also, knee injuries will permanently fuck your shit in ways few other injuries can. Armor them knees up.
You might be able to get away with shoes at low speeds, but I've seen multiple riders have their foot ripped off at the ankle in crashes. Shit ain't pretty. For what it's worth, I'd highly recommend boots.
Headphones are fine, just make sure you keep the music low enough to hear stuff around you. I'd look into getting some sound cancelling earbuds, or some other headphone you can wear with earplugs. Earplugs are very important if you want to be able to hear later in your life; even 30mph can result in hearing damage without some kind of ear protection.
I wear glasses when I ride. Some helmets can be kind of a pain to wedge glasses into, but it's not too big of a deal.
Lastly, 3 more things of equal importance:
1) If you haven't already, take the MSF, or whatever your state's version of it is. A motorcycle safety course will teach you valuable skills and save you some insurance cost.
2) PRACTICE PRACTICE PRACTICE. 30,000 miles of riding later, I still do this regularly. Find an empty parking lot and practice emergency braking. Get your stopping distance as short as you can without locking the front or rear wheels. Practice swerving to avoid obstacles. Practice low-speed maneuvers. Practice.
3) Have Fun!
Congratulations again on deciding to ride; it may end up being the best decision you've ever made!