Johnny
1 - yes
2 - Define Biofuel.....if fat derived esters, up to 30% or you risk smelling like a fish and chip shop.
3 - any liquid hydrocarbon risks a spill, lub being the worse...with fueloil (though what would fuel oil be doing on a road)
4 - Fuel Oil is something else all together, full of very long complex hydrocarbon chains (and from which lubricants are sometimes extracted) - huge boilers such as in ships and power stations use it and to ignite it, they actually burn diesel to start with to heat the boilers. Also, diesel is less polluting in ports and near to shore, though there has been a lot done to reduce things like sulphur content (in the trade you will find LSFO and HSFO with corresponding price differentials.)