Attached Link: http://www.renderosity.com/mod/forumpro/search.php?query=hair+grass&forum_id=&sort=relevancy&use_age

The Dynamic Cloth and Hair tutorials hat are included in the Help files are as good a place as any to get familiar with those "Rooms" and the Wind Force that you'll need to animate hair grass. Use negative gravity to make hair grow upwards. The link below is a thread search for Hair Grass, you might find more detailed help there.

Animating trees is dependent on the tree model, props or figures may need to be treated differently. Leaves are frequently trans mapped planes, sometimes branches too, so deforming them may be problematic. The simplest way to bend a tree prop would be to use a magnet or two.

Fluttering  leaves, again depend on the model but I'm wondering if this could be achieved using animated materials, high/low specular light or adding black or dark green at low levels in the ambent channel. I'll give that a try next time I've got a tree in the scene.

Searching the marketplace for morphing trees might give you some ideas too