In radiant, is there any way of selecting a load of bushes (but not every brush in the map) all at once?
Draw a big block (with any texture you may want), then right click (with the big block still selected) and choose select-inside. The big block will disappear but every brush that was inside it is now selected. You can also use select-touching. That won't remove the root (to be touched) brush.
Another option--hold ALT and click-drag a box to select everything inside that box. The disadvantage compared to "select inside" is that you don't have 3D control.
Or press "T", select a textur, then press "ESC". Now you can select all brushes with the textur you selected with "Alt + A" ;)