The GPL License: If you distribute software derived from other GPL software, then you must also distribute it to under the terms of the GPL. That goes for the code snippets too. If you absolutely must use those snippets, you could go to the copyright holder of the original code and ask for a separate license for your needs. You may need to pay, but it may be worth it.
The BSD LIcense: If you use the BSD-Licensed Kohana Framework, then you must give attribution that you are using or deriving from the Kohana Framework. But you don't have to distribute any of the source code.
If you are using code snippets from the GPL project, it will be very hard to prove that you swiped the code. In fact, if you change function names, variable names, and the order of some statements, no automatic code analyzer will be able to conclusively show that your snippets were originally from the GPLed software. You can check this very quickly by dumping the symbol table of the original software and the symbol table of the derivative work and comparing the two. (e.g. by using the Linux "nm" utility). You should not do this, of course, but if somebody did it to software you owned, but licensed under the GPL, you would find it hard to prove it.
Proving GPL violations in court is very hard. Most companies caught violating the GPL were caught because their developers (often outsourced) brought in open-source components to develop or test the software, but failed to strip out the software, or to strip out the symbol tables from the build, or change method signatures, magic strings, or logs produced by the GPLed software.