Animating using NLA and non-slip walking on a path - how?

I have bunch of Actions I created for my game. However, now I need to animate same game character in Blender for a short movie.

How do I go about combining all anims I’ve created into seamless motion using NLA editor?

Also since all of my Actions, especially walk/run/etc. cycles are animated in place, how do I go about having characters walk around using path and making sure feet don’t slip and plant firmly ?

Thanks.

Maybe I can be pointed at a good tutorial ?

there is no good tutorial (i know about), but if i assume your
animation in place is really a good animation,
like such created from bvh-anims, then
you should search the forum for the usage of such anims.
I think batFinger did provide some scripts to path those along a curve
and i am shure if you search for threads with postings from me, there are some
samples too (most for older blender-versions, but the background is always the same).

The background is, to sum it up:

a good animation in place is the same as this animation with a steady movement in the translation direction. For example i transfered the walk-animation in place from some bio-motion-website to a walking animation along a curve. But its not easy.
You can do it by hand and position the character with a steady speed along a line - thats the first way to try and check if your animation-in-place is easy usable with a steady (constant?) speed. If not – you would need a changing speed from frame to frame … and this is nearly impossible. Thats why normaly the way is done from an not animation-in-place. From a full walk animation one calculate the steady/constant speed and then it is just translated into an animation-in-place (look for batFingers script sample) this can easy set up with a repeat factor and an constant speed along a curve etc.