What can I do to reduce litter box smell and tracking???? HELP

Background:  We have two cats, both female.  We have two, covered
litter boxes.  The boxes are side by side and both use by both cats. 
We clean the litter daily and replace it every couple weeks.  We use
premium, clumping litter (fresh step).

We have two problems:  

1.  The litter gets tracked across the floor.    How can I reduce
this?

2.  The smell, what can I do to reduce this?  We have a air cleaner
running next the boxes with a HEPA and Charcoal filter.  This seems to
help some.  The younger cat (7 months) has a habit of not covering her
waste.  This definitely adds to the problem.  It's not too bad but you
can definitely smell the boxes in the room.

Thanks for the advice.