One should never crank an engine with the coil wire disconnected. Many modern electronic ignitions can be damaged if the secondary circuit is open. IIRC the Mercedes service information has a warning about this as many others do. If you want to disable the ignition, disconnect the 12V power to the switching module.

A proper Mercedes oil filter has both an anti-drain back valve and the bypass valve. Only buy a proper Mercedes spec oil filter like the Bosch 72165 from a reputable Mercedes parts specialist. Many McParts oil filters including "Bosch" brand that Autozone carries do not meet the OE spec even if their catalog calls out a number.

After an oil change, start the engine and hold about 1000-1200 revs. The oil pressure should rise within about three seconds.

A ticking sound on statup may be due to lifter bleed-down or a "sticky" lifter. If you believe the internals are dirty and may have some lifter clogging I suggest you continue to use CI-4 oil.

Duke