just some general and specific questions about running a business which uses open source software and sells training, services, and other value added solutions utilizing the open source asset(s).

1) how much modification do you need to make to an existing open source software/framework to give a new brand ? open source (GPLv3) branding issues here.... for ex) Mambo and Joomla, i think they are pretty much same ? but they have different labels.

2) Is there a disadvantage of promoting open source software/framework/suite in hopes of selling value added services and solutions on top of the Open source asset ?

3) can Open source assets be marketing point for lowered Total Ownership Cost and transparency ? meaning, clients will not be using some mysterious, opaque proprietary asset ?

4) is competition fierce? cost of developing software is non existing because you are using an open source asset. barrier to entry is minimal ??