Can Conditional Formatting be applied in all sheets?

Can Conditional Formatting be applied in all sheets, not only one sheet?

Only for every sheet in the same way. Conditionally formatted ranges belong to only the one sheet they were defined in. If there is used a formula it may, however, refer to other sheets, too.

(The present ‘CF-Manage’ dialogue allows for entering ranges of “cuboid” type. These aren’t recognized anyway.)

This limitation is a deliberate decision: https://bugs.documentfoundation.org/show_bug.cgi?id=52196

Yes, but that concerns the range of conditional formats manageable from one sheet. References into other sheets for a comdition of the ‘Formula Is’ type are allowed.
My remark concerning “the present CF-manager” was valid on 2014-06-30 and pointed out a little inconsistency. As I just tested the inconsistency still exists (without doing any harm except to my soul).

Hope this function could be added in future version.So we don´t have to copy same conditioning formatting for each sheet.

  1. Conditional formatting as we presently have it seems to be half-baked at best. As long as it doesn’t reliably work with the given set of features improvement with this respect should be in the focus. About additional features later.

  2. If you have many sheets and make extensive use of CF: How shall the manager provide access to all the ranges and how will you edit them correctly as long as the collection of equally CFfed parts is as inadequate as it is?