Is there a way to add a line of text in a color other than black?

I am using a NUVI 350 and have solved (thanks to POI FACTORY) the problem of line breaks.

Now I would like to jazz up certain POI's with a color (like red) to call attention to some significant item for a particular POI....

It's certainly possible. However, for most consistent results, gpx input is required, rather than csv.

The Nüvi and later Streetpilots understand a cutdown form of HTML called GML (Garmin Markup Language). You will probably find some examples of its use within the help files on your Nüvi.

The main issue, is that most units only interpret GML in data that appears on Page 2. Page 2 only appears when Page 1 has already been used by Address data. CSV files do not give access to the Address fields.

However, the Nüvi 3xx series is somewhat different, in that it only has a single display page. As you have found, with the use of <BR> constructs - it does interpret GML.

However, the 3xx series has a different issue: the "comment" field (which is what a csv file's 4th column targets), is truncated to somewhere around 250 characters. Worse than that, this truncation is applied to the raw data - rather than its result.
So the string

<FONT COLOR=RED>RED</FONT>

counts as 26 characters, rather than 3! - rather limiting its usefulness.

This truncation is not applied to GML in the "description" field, but as mentioned earlier - you have to use gpx input to access this field.

Example output:
http://GeePeeEx.com/Colours.JPG

Your example is what I am looking for, but I have never used GPX

Can you direct me to some threads that could get me started?

Just download GeePeeEx Editor at http://geepeeex.googlepages.com/