They actually had more soldiers than was shown on TV.
is correct. The singular "was" is used because reference is being made to the fact that they had more soldiers, or to their having more soldiers, which are singular subjects. The plural "were" is also possible as stated by Edwin Ashworth in his comment, the only slight difference being, in ...
The subject is the relative pronoun "what," but in this case it must take a plural verb to agree with "steps."
What I have presented are the first steps.
The same holds if you invert the sentence:
The first steps are what I have presented.
To further clarify, the sentence also doesn't make sense at all if "what" is substituted for a singular noun. You ...