Complex riddle!

This puzzle is in 5 parts.

Step I: what 2 letters come next in this sequence?

ZEROFIFTYONEFIFTYTWO FIFTYTHREEFIFTYFOURF IFTYFIVEFIFTYSIXFIFT YSEVENFIFTYEIGHTFIFT YNINEFIFTYONE _ _

hint: the answer isn't "FI." None of these are particularly easy.

Step II: what 2 letters come next in this sequence?

ALAC.
CISE.
PAEN.
SASA.
RODI.
THWI.
TATH.
OR.
_ _.

Step III: What two letters fit in the gap in this sequence?

KI
PH
CL
_ _
FA
GE
SP

Step IV: take these six letters and erase all instances of the letter "A."

Step V: Arrange the remaining letters into a common English (There are 2 possible words)

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My friend asked me to try this, but I have had no luck. (Besides on part one, ZE)