Hi~ I saw this article while roaming through expat-blog, and thought I'd offer my two cents:) I've recently relocated to Osaka with my husband (who is Japanese, so my experience might vary from others significantly, sorry =/), so these are just my first impressions. Hopefully someone may find them helpful~
Also, @DCosaka, I'm from D.C. too! I lived there while in college and was raised 20min outside of D.C. in Maryland =]
Anyway, directly from the states looking to get into English teaching is quite difficult. Most of the time, if you're being interviewed from overseas, they want to place you in rural cities because a.) no one who's already in Japan (in big cities) wants to move out there and b.) people coming from overseas generally don't have much of a choice. Also, I noticed on a lot of job postings that a lot of schools require some kind of certification like CELTA. This is probably a big result of all the chain English schools that have gone bankrupt:( (NOVA, GEOS)
Also, in terms of how Osaka is set up, there is Osaka the city, then Osaka the prefecture (more like a semi-prefecture maybe, it uses the kanji 府 instead of 県). So if you're talking about staying in Osaka, you might need to specify Osaka City if you mean near areas like Namba, Shinsaibashi or Umeda.
For apartment hunting, there are quite a few shops in Osaka City that cater to foreigners with English-speaking agents. The one shop I actually went to didn't even try to speak English to me, so I'm really not so sure about that claim:/
I ended up going to a regular shop (like Apaman Shop or Homemate) with my husband and just doing it traditionally. When we got our apartment paperwork though, we were required to have a co-signer and show proof of work and being able to afford the apartment. I'm gonna assume it's the same when they deal with strictly foreign customers since I have two friends from France looking for a place, but they need proof of a job first (they're on working holiday visas). And usually your company will act as your guarantor (co-signer).
If you end up getting a foreigner apartment (which I would recommend if you only intend on staying for 1 year or so), it'll probably be furnished or partially furnished (bed, fridge, tv, maybe internet). If you just want to get a regular apartment, then you may need to buy things like a refrigerator, stove top, microwave, tv, bed, couch, curtains, etc. A lot of money~
Let's not forget key money, and that can go up to 2K easy. But it varies greatly because sometimes you don't have to pay at all.
The busiest areas of Osaka are probably Namba, Shinsaibashi (America-Mura), and Umeda. That's where all the clubs, bars, and shops are located. This part of Osaka is mostly Naniwa, Nishi, Tennoji, Kita or Chuo Wards. If you stay in any of these wards, it's more likely you'll be able to get to the downtown area easily by bike or on foot. But since most of the clubs run from 11pm to 5am, you could easily catch the train out to the 'burbs afterwards:)
As for me, I usually walk (or bike) home from a night of clubbing, and I've done so several times feeling totally safe. Though I've stopped recently since it's so cold =] I don't know if coming from D.C. gives me the impression that Osaka is completely safe though... You should always be careful though.
Umm.. that's just some basic info I could get off the top of my head, so I'm sorry if it seems a little confusing:| If you'd like to know anything more, I'll try to answer =]
Cheers~