> 1. Trying to remove the first and last element in an array in Ruby:
> def remove_ends(a)
> a.pop
> a.shift
> end

Is your problem, that a gets altered?
If so, try
def remove_ends(a)
  a[1..-2]
end


> 2. I'm trying to interleave 2 arrays. I've seen some examples online but

a = [1,2,3]
b = ['a','b','c']

a.zip(b).join  # => "1a2b3c"