My questions are could this split be causing the soot, is the black residue normal around the split or a sign of a faulty turbo bearing and is the cruising smoke something to worry about. Plus will the split cause any impedance to performance.
Yes, not necessarily, yes. Yes.
Black smoke is a sign of over-fuelling. Because you're leaking air out before the engine, you now have too much fuel - hence smoke.
A little oil misting inside the boost hoses is completely normal, and it tends to get dirty/sticky around a leak. Excessive oil can be a sign of something more sinister though. As you describe it however, it sounds normal.
Prolonged running with your air/fuel ratio out f whack could cause issues with the cats/lambdas etc... Engine was meant to run with the boost going in, not leaking out!
Again since you've got air leaking out, the fuel isn't burning properly.. Hence the power you get from each burn stroke is lower than it should be. Lower power, lower economy, and a smokey mess out the back!
Upper hoses are easy fixes.. Autolusso sell top quality silicone replacements that come with a lifetime warranty... Alternatively seek out a rubber replacement for a few pounds and run it on a bit longer...
Ultimate cheapo repair involves duct tape or self-amalgamating tape, and wrapping it up closed... Not by any means a worthwhile long-term fix... But taped up whilst you wait for the spare part to arrive is perfectly acceptable.