I guess the two things I ask for:

1) How can I change the font type (eg into Consolas) ?

You can change the font in the CSS file (style.min.css). Search for the rules of div.posting and set a rule for the font property (font: monospace;). If the headline (title of the posting) and the authors info should be displayed with "normal" font, set the correct font type for div.posting h1 and div.posting p.author.

2) How can I disable the forum's merging of consecutive spaces into into just a single space?

That's a feature of HTML. You can use the bb-code codeblock to generate a table.

--------------------
| id | description |
--------------------
|  1 | one         |
|  2 | two         |
| .. | ...         |
| 11 | eleven      |
--------------------

Tschö, Auge