Yes, it can cause hard starting.
The first thing that comes to mind related to those symptoms is a blown head gasket.
I blown head gasket can cause an engine miss which one cause a rough idle.
No likely but possible if coolant is leaking out onto some electrical component.
yes if its stuck closed.
Yes, I blown head gasket will definitely effect the emissions.
No, a normal tune up cannot cause a blown head gasket. A blown head gasket normally is caused by an engine overheating or by a defect in the gasket or head. If it happened right after a tune-up that is just a coincidence.
The car will start but it will run rough and will probably overheat and cause worse problems.
yes
the answer is yes
No
It is not wise to drive with a blown head gasket. If you continue driving with a blown gasket, eventually your car will over heat and the engine will seize up. This can cause accidents if it occurs while driving.
It can as one or more cylinders may have a misfire. A blown head gasket will destroy your engine.