Can any diesel vehicle be converted to SVO or drive on Bio-diesel?

Yes and yes. If you are burning a lot of fuel, the SVO conversion is for you. You will keep your diesel tank to start and stop your engine. Once the engine is really hot, you flip a switch on your dashboard and start burning veggie oil instead of diesel. When you stop for a longer period of time, you switch back to diesel to flush the veggie oil out of the engine so that when the engine cools, it will have diesel sitting in it.
If you are not going through a lot of fuel, bio diesel is the way to go. You will save yourself the money for the conversion and you could put it towards setting up a little workshop in your garage to make your own bio, or you can purchase it at certain gas stations for about the same price as diesel, or you ask around and find someone who makes their own bio diesel and buy their home-brew from them.