I can't fully answer your question, but I can help you to stop wasting time on certain mistakes....
I had Ubtuntu 14.04 LTS installed (with encrypted homefolder) as dualboot with Win8.1
of course all the time my BIOS settings where on Secure Boot Disabled, and Launch CSM enabled.
On a computer that shipped with Windows 8 or later, chances are you should NOT be enabling the CSM (aka legacy support). To understand why, first know that you do not have a BIOS; you have an EFI. I know that most people, and even most manufacturers, refer to their EFIs as BIOSes. This leads to confusion, though; EFIs are fundamentally different from BIOSes, and using the term "BIOS" to refer to an EFI leads readers to drag in all sorts of BIOS knowledge that's simply wrong when applied to EFIs. The result is people confidently doing things that have worked in the past but that create new problems on their EFI-based computers.
Most modern EFIs include a Compatibility Support Module (CSM), which enables the EFI to boot using a BIOS boot loader. This is something like Linux using
dosemu or WINE to run DOS or Windows programs in Linux; it's a compatibility layer stuck atop another environment, but it doesn't make EFI a BIOS any more than
dosemu makes Linux DOS. Worse, activating the CSM greatly complicates the boot path, making it next to impossible to predict what the computer will do as it boots, at least when it's fed a medium (such as many Ubuntu installation media) that can boot in either way. Will the Ubuntu installer come up in BIOS/CSM/legacy mode or in EFI/UEFI mode? Who knows!? Flip a coin, and don't find out until it's too late, since the boot mode is obvious only if you're an expert! Sorry if I sound sarcastic, but I've seen far too many problem reports related to this issue. See this Web page I've written for more detail on the CSM and the complications it creates.
The bottom line, though, is that you should go back into your firmware and disable the CSM. Ubuntu should work with Secure Boot active, but it sometimes causes problems, so disabling it can have some benefits some of the time. OTOH, it also provides at least theoretical protection against some modes of attack, so it's best to leave it active if it doesn't cause you problems. (Problems should be obvious very early, since the system won't get as far as GRUB if Secure Boot blocks it. If it gets past GRUB launching a kernel, it's not a Secure Boot problem, at least not on Ubuntu.)
I should provide a caveat to all of this, though: The CSM is necessary in some cases, either because you've re-installed Windows in BIOS/CSM/legacy mode or because you've got hardware that requires BIOS-style initialization to work correctly with a Linux driver. Such cases used to be moderately common, but they're rarer today.
I tried boot-repair in Ubuntu rec mode, that killed it completely. After that it said missing file when i tried to boot.
It could be that this is related to your CSM activation, but I can't be sure of that. If you want help with this, run Boot Repair again and post the URL it spits out.
So i formated the Linux partition, assigned that free space to a new partition B:\ and booted a Windows-Installation-USB, went to command prompt and executed:
That's one of the BIOS-specific commands that doesn't work with an EFI-mode boot. Basically, this command re-installs the BIOS-mode Windows boot loader to the Master Boot Record (MBR) of the boot disk. Because an EFI system boots in a completely different way, this command has, at best, no effect on an EFI-mode system. A caveat: Because the CSM introduces unpredictability into the boot process, it's possible that installing a BIOS-mode boot loader in the MBR will cause the computer to try to boot in BIOS/CSM/legacy mode, which would just end up causing further breakage. Depending on what the problem is, any number of Windows or non-Windows commands might do something analogous to the command you specified. The main point, though, is that you need to track down EFI procedures to fix boot problems, rather than use BIOS procedures.
How do i remove the Ubuntu boot options that still show up in BIOS?
If you're referring to the EFI's boot manager menu, you can remove these from an EFI-mode boot of Linux. Type
sudo efibootmgr to see these options (or
sudo efibootmgr -v to see more details). Each option has a hexadecimal number, preceded by
Boot, as in
Boot001B. You can remove an option with the
-b # and
-B options to
efibootmgr, as in
sudo efibootmgr -b 0003 -B to delte
Boot0003. There are other ways to do this in other OSes. In Windows, EasyUEFI is a third-party tool that, as its name suggests, makes such manipulations easy. Some EFIs themselves provide such tools, in their setup utilities.
whats the Problem with my Notebook that Ubuntu didnt work and no Linux live USB launches anymore?
I don't recall seeing your specific issue before, but it looks like either the hardware is defective (either a bad sample of your model or a bad design that affects all samples of your model) or it's new enough that it's not yet supported by the kernel you're using. You say you installed Ubuntu 14.04, but you don't say if that was the original or a point release (14.04.3 is the latest). If it's not 14.04.3, I'd try that; and if that doesn't work, you might try a 15.10 pre-release; see here for download links to the daily builds.
There's no evidence that this error has anything to do with EFI, although some of your repair attempts complicated matters by creating CSM-based complications.