Eventually it will come.
should be "vársz egy almára"
Could be, yes. Report it.
Can the indefinite article be dropped in this case? "Vársz almát"?
Yes, but that's another sentence: "Are you waiting for apples?"
Would "Almát varsz" also be acceptable here? If so, would that alter the meaning?
Why "almát" and not just "alma"
Here 'alma' is the direct object so it must be put into the accusative case = almát. (This whole unit of DL is about the accusative case, so you will notice many nouns adding a -t.)