Hi (your first post) Welcome
Your FreeCAD version is obsolete, 0.14.3703 was released a while ago. Being on Ubuntu I would recomend that you install the daily version from the PPA and get all the advantages of the latest features and bug fixes.
This page in the FreeCAD wiki tells you how to install the daily PPA.
http://freecadweb.org/wiki/index.php?ti ... A_packages
mlipinsk wrote: I found it nearly impossible to remove sketched pockets/pads done "few steps earlier" without falling into problems.
generally you can not do that when using the PartDesign Workbench. Minor changes should be OK but anything that changes the number of edges etc. will cause problems. If you have to make other than minor changes in your history, you have to delete all the Features past that point, keep the sketches, and re-map the sketches to the faces and make new features again.
OS: Ubuntu 14.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.15.4207 (Git)
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.7.1.oce-0.17-dev