RSS with restricted word limit or custom field

I’ve been searching on google and on the forums for about 3 hours and I couldn’t find an answer to what I want to do.

So I’m making a site that has job listings. On the main page I want a feed that people can subscribe to in order to get updated listings about jobs. Here are my problems:

On the main page I have a three column layout. The first column is for their legal department and basically pulls out each news post that is tagged with a legal tag. The second is for the employment department and the third is regular news, again all just using tags and categories to sort what goes into each column.

I’m using a plugin to limit each of these column lengths to xx amount of characters so that it then has a ‘read more’ link. For this reason I do not use the ‘excerpt’ field in wordpress, as it’s just automatically doing it for me from the main post content.

Now in the RSS summary I want it to be something like this:
Job description:
This is the brief description of the job

Then you click on the job description title to go to the full entry. Their existing system does this and it’s been quite popular so this is how we’d like it to remain. I’m really not sure how to do this best though.

I think the easiest way would just be to have a word limit. At the moment I understand it’s set to 50 but it seems there’s no changing that limit no matter what I try.

On the other hand I’m worried that having a word limit will truncate something really important, and maybe it’s best for them to make their own custom short blurb, maybe even with a limit so they can’t write more than xx words. That idea really appeals to me the more I think of it. I have absolutely no idea how to go about it though!

So in short I want to make something like this:

Legal Secretaries (link)
Legal secretaries, location x, $16000-18000 a year, must have 2 years experience

Max word limit (e.g. 40)

And it has to be easily updatable from the news post editor in wordpress. I don’t care if it strips code as it’s only going to be plain text snippets. I’ve managed to do everything so easily on wordpress so far so it’s just frustrating that I’m getting stuck at the final hurdle. Thanks for the help in advance ??