The oil could be from the breather - the breather coats the inside of the boost hoses and the intercooler with oil (where it condenses) if a boost hose splits, this oil can spray out

It is "normal" for the inside of the boost hoses and the inside of the intercooler to be coated in oil, exessive amounts could mean ring, bore or valve guide/ seal wear, or turbo seal failure, but the "normal" anount iof oil from the breather can build up over time

A split boost hose or EGR (inlet/ intake side) should blow out air (it should be pressurised by the compressor) not suck air in on a turbo car (NA engines would draw air in from the EGR)