not streaming on on an notebook with an hyperthreaded dualcore :/
but if you have to i would say start with
540p
30 fps
cfr and cbr checked
bitrate/buffer 1500
maybe you even have to chose a faster preset (superfast or ultrafast) but you will find it out as soon as you try some streaming. maybe you might even get away with 720p30 on ultrafast but then you would need to use like 2500-3000bitrate which is quite a bit for your upload and will probably end up with ping spikes
see how this goes i highly doubt that this cpu can handle 720p30 properly while trying to game on it