I hope I could understand your questions well.
-About the menu, it's not an option to show different menus in the blog, but it's possible to be done with some mods.
-The slider in jobright is built-in, not a plugin, however, it's possible to be integrated into olinda or jobsapp (it requires some time + some skills)
- We created a separated menu in wordpress dashboard to manage the sliders' pictures and content, and YES, You can add links,texts,and pictures), setting the width and the height it's not an option ,but some 2 changes in css file, this can be implemented.
For the pictures themselves, it doesn't matter what's their sizes, they be cropped with the same size of the slider.
- Our themes use same language packages of jobroller, and I believe there is full translation version for Jobroller here
Except for jobsapp that we included few words to it that they easily can be translated using the dutch .po file.
I hope I answered all your questions