yeah, thats right. But 1.86 Ghz on 2 Cores are not enough I think.
To run OBS: Okay. But to Stream and maybe Gaming on the same Time not.
I have a 3.16Ghz dual core on which I sometimes record + stream while one of the processors is almost completely tapped out by my game. So I think a 1.86Ghz dual core processor should be able to handle just OBS, for streaming at a low bitrate it won't look too great though. The biggest issue is overheating, but that can be circumvented by making sure the fan is on a flat surface that doesn't get sucked in.
If this laptop is the only option you have, it will work. If you were going to buy it to stream, then don't because it's extremely borderline for streaming.
Now, to your setup: On a low-end machine, downscaling is a horrible idea. Make your setup in 480p (or 360p even) and stream that directly without scaling. FPS should be 20 or 30, bitrate as much as your internet can handle (but not above 2000). Use Profile: High, the slowest CPU preset the laptop can handle (probably either superfast or ultrafast), and the following x264 parameters: tune=film rc-lookahead=10
Oh, and get Chatty so you don't need to have your browser open while you stream.