1. if the pipe is soft means it's delaminated so you need a new one
2. if that pipe is too oily there is excessive cranckase gas or the depression control valve is stuck open, only way to rule it out is to replace it with new but remove the oil filler cap at idle and see what happens
3. if the injetor harness was aftermarket 9 months is good enough, i've seen cheap ones leaking after 3 months, genuine is the only reliable
4. if you mean the starter solenoid wire tighten the connector or replace it with a new one cos they used to get soft but the core plugs have nothing to do if it's oily cos they are for coolant, i have no ideea what kind of a job it is.