how to merge two csv files in a template word document?

[BearPalm]

Hi, everybody.
I have one input csv file and another output csv file.
I'd like to merge them into a word template document
to create a report. I'd like to write a macro in this
template document, however, I meet following problems.

1. input and output csv file names are dynamically changed,
even though input files and output files have same format
respectively.Is it possible to merge them in programming?
I mean if I use merge-mail method to create the report,
I had to use an un-changable file name(hard-code) to open
data source for defining fields. If I use same file name,
the data may be overwritten.

2. if 1 is impossible, I had to use merge-mail method
to create the report. however, I have two csv files.
Can I use the two csv files as data source?

3. if using merge-mail skill, how can I run a macro
automatically when the template document is setup?

I am quite new at VBA development ( one day?) .
When you reply this post, please give me some sample code
if possible.

Thank you very much.

Jeff