Transform a Column to a String

[vznamenskiy]

Excel (Google Sheets)

1. How to convert column to string?
2. How to transform the column (or row) by putting after each element one more element with the specific constant content? For example, replace
a, b, c, d, e, f
on to
a, x, b, x, c, x, d, x, e, x, f, x,
3. How to unite two adjacent columns into one column in the following element order: a1, b1, a2, b2, a3, b3, ...?

[#2]

@vznamenskiy 

This became straightforward with the introduction of the TEXTJOIN function.

= TEXTJOIN(",", 1,column)

For a string "x"
= TEXTJOIN(", ", 1,column&", x")
or a cell reference
= TEXTJOIN(", ", 1,column & ", " & x)

For two columns of data
= TEXTJOIN(",", 1, data)

[#3]

@Peter Bartholomew 

For #2 it could be

=TEXTJOIN("x, ",1,1Drange)