In multiplayer do you think you will move slower an maybe not be able to slide or stuff when using full armor?

Yes. That just makes sense. If your holding a LMG then you shouldnt slide, it only makes sense. Also I think the slide is a armor module.

You do move slower, you can see it some of the MP vids. Not sure about sliding though.

Sliding isn't a suit module. The list of classes shows the modules for each, and there are no special sliding ones.