If a judge has already made a ruling on an issue of substance (not an Ex Parte usually) then you are stuck with that judge. If this judge has not made any rulings and not heard any matters, you have within 10 days of the assignment of judge to ask for a new one. (170.6 Disqualification of Judge form). You get a new one without the need to say why. BUT you can only do it once per case. If there is a Judge that has an actual bias or conflict you can always Motion to have them removed but it takes a lot. I totally agree that you should be careful, the next one you get can totally be worse.
It depends on how old your case is, whether there have been any hearings, whether both parties have appeared in the case yet. See Code of Civil Procedure §170.6. That being said, be careful for what you wish for. You could end up some place worse.
Generally, no, but why are you trying to do this? If a judge has already made decisions in your case, and your only reason for wanting to "transfer" is that you don't like the judge's decisions, then the answer is almost certainly no.
You can use a peremptory challenge under CCP 170.6 but it must be within 10 days of an all purpose assignment. There are other options beyond CCP 170.6 but you'd need to supply more information to receive a more detailed response.