When do you know to get out?

Most everything listed is a normal wear and tear/maintenance item. With something that old belts and hoses should have been changed years/miles ago as a preventive measure. Suspension, bushings and countless other things fall in that same category. Anything can fail whether new or old but with an older coach much more attention needs to be paid to wear items. The alternative is waiting on the side of the road and then soon after watching a mechanic tell you everything that needs to be done. If things were maintained and or repaired/replaced on a consistent basis you would most likely be looking at a solid coach with a different view of its reliability. Good luck with the repairs.