Functions to sum alternating columns, every third column, for all rows, etc.

Hi guys. I am a complete beginner. I have all my data entered but I don't know what to do with it.
Here are the things I need help with. If you could help with ANY ONE OF THESE THINGS I would be extremely, extremely grateful.

First of all, for some reason columns BZ and CA are missing. I'm not sure why and there is no data in either of those two columns. How do I make this go back to normal? The column heads are blue.

Also, I have MISSING DATA. I would like the sum function to treat these as if they are 0s, but that count function to not count this.

1) I need to sum the values in every other column between E and CB. So I need E but not F, G but not H, etc. All the way to BY (because BZ and CA are missing). I also need to count the number of cells with values in them, and hopefully get a ratio of sum/number of non-empty cells.
I need to do the same thing for two other sets of columns.
I need to do the same thing, except every third column, for another set of columns.


2) Is there any way to repeat a function for all rows, or for rows 2-10, for example?

3.) I need a function that looks at two different cells, inputs into an existing column nothing if either of the cells are empty, enters a 1 if they match, and a 0 if they do not.

4.) Is there any way to call up columns? For example, if the column name contains 'ify' or something. Column headers are my first row.

5.) Is there any way to add a call-tag to certain columns? like every other column in the first eighty columns would be called 'List A,' and whenever I want to sum or perform statistical tests on just those values, just call up List A?

That's pretty much it, I think. Please, please, help.

edit: adding attachment.