Aeronavigant,
Here is how it basically works in the states. You get your Comm/inst then you get your CFI, II, MEI and build time teaching. If you have 250 hours, that is probably your only course of action, or banner towing. The lowest minimum flight time requirement I've heard of is 500 hours up at LAB flying service in Alaska. 500 hours total required and you're flying PA-28s (160 or 180) to and from small villages VFR. (Okay VFR in Alaska is a joke, there is no such thing if you're trying to keep schedule, but that is the certificate under which they operate).
So you have a lot of multi time compared with total time, good. Some interns might be getting on at certain carriers with less then 500 hours, but they were interns. At the crappy companies I have suffered with, I flew with an intern 750 TT, he was a lot better then some of the 2000 hr guys. I want to reiterate that I am not making any comment on ability here, I flew with a guy who said he had 17,000 hours - after flying with him I thought no, you've got 1,000 hours repeated 17 times.
GLA and Mesa have very low entry requirements - I'd try there first as an F/O. The money you save on a type you're going to need for groceries because the pay is crap.
Keep asking, but if I were in the hiring department and my company flew 1900s and two guys came in with 300 hours, one with a type on the 1900 and another with a different type, I don't know that I'd be so predisposed to hire the 1900 guy. You have to send them through the same training anyway, regardless of previous types, and they both have demonstrated that they can learn an airplane.
Tough question, there probably isn't a correct answer. It sounds as though your mind's pretty well set on the 02 type, so good luck.
Let me then ask you what specific company do you want to work for that flies the 1900?
Ask their chief pilot what he/ she recommends.
If you do go for the type remember to have fun and fly with a smile on your face, (releases tension and gives you better SA). This is a stupid career path if don't love airplanes or you're not having fun.
About the training (I suppose that's a typo, it's 121). You'd be going not as an employee but a contractee for a type rating (we only have captain types here, a type is a type is a type)
Well keep in touch, let us know what you've decided.