The_except() on category posts

Hi there
Have a small question

On my webpage i have a sidebar. A category list.
Some of the posts in my categories have a long title.
Is there at way to set a max. length or maybe (except) / read more.
on a category sitebar widget – and where in my files should i look. ?

you know like : bla bla bla bla … read more

Also in the same category sidebar widget, i would like to have
a featured images, from one of the posts in the category.
(Ex. the first image).

Any of you made some code that can do that?
Really not much for plugins.
I would like to code it in

Really hope some of you can help

Cheers | C yaaa
Kimo