Yes.
It will usually cause severe vacuum leak(s). The fuel will not enter the system correctly and the vehicle may not even run,
Yes, if installed improperly.
What is a Vacuum Leak ? A vacuum leak is any leak caused when sucking in Air either after the throttle plate of a carburetor or after the Air Metering device on a Fuel Injected car caused by a bad gasket, torn boot, improperly installed adapter plate or manifold gasket, etc
Improperly installed gasket, failed crankshaft seal, stripped bolt, warped timing chain cover, dirt or grit between the cover and the block... that's just a few ideas. I wish I could help more.
Yes. If an intake manifold gasket was not installed properly or has somehow become damaged the engine will pull air through the opening.
Yep.
If the leak is bad enough i believe it can but i would check your valve cover gasket first.
yes it can
Sounds like a possible oil pan gasket leak, also check around the oil filter and make sure that it seated properly when it was installed.
Blown head gasket
You have a gas leak, installer may have damaged or improperly installed gas line.
If the casing is spilt a filter will leak an incorrectly installed filter will also leak.