these parameters must be same in Chromium Based Browsers, right?
why I get very different results in Opera, UC and etc....
You should ask it from the developers of these third party browsers (did some research but couldn't find anything and since each of these browsers have different features of their own, then most likely the parameters are different too).
also, why Topics styles look different when previewed than posted?
The only difference that I notice is, when you preview images that don't have their appropriate links in comparison to those that have, it's shown normally but upon posting the thread, those images that don't have links, tend to be off a little (either higher/lower or pushed in right and left directions).
There were few threads in regards to this issue, couldn't find it though (will link it here, in case I'll find it)...
Did you experience something else in regards to threads behavior prior and after it's created?