b.) you wouldnt be able to. You would have to install it to the OS that is working so that you can add the entry for the 2nd OS. There is no way to install it to the other OS that isnt working. Plus if both OS's are working, it negates the need for EasyBCD.
c.) Voided by answer to #1.
d.) So what if NeoGRUB is used and partitions are hidden? You can still dual boot. If you can get into 1 OS that EasyBCD is capable of being installed to, then you can dual boot. I dont get this question at all as there is no real question.
e.) You dont need anything but the partitions used to install the OS's on and a functional MBR. I dont have any ESP partitions.
f.) EasyBCD is just a way to work with the BCD that is used with Windows Vista, windows 7 and Windows 8. It will show only a boot menu with options to select the OS to boot to. It doesnt do anything more than that. It is completely limited to what can be done by the BCD itself created by Microsoft.
g.) That depends on the OS being installed and has nothing to do at all with EasyBCD, read answer to last question.
h.) XP doesnt require IDE, it just doesnt have drivers for SATA. But you can install them using the F6 option during the install process. So you can use ACHI with XP, you just need 1 extra step. The option to restore depends completely on you. If you get rid of the recovery partition, then no you cant restore. The Asus Recovery partition is not something that we are responsible for. As stated, we only give users a way to work with the BCD, nothing more, nothing less.
The issue with the BIOS, is not related to EasyBCD. I hope you do realize this. The BIOS starts up before the BCD menu and anything that EasyBCD has an effect on. So the issues you present are something that would come around from Asus and their BIOS. It isnt until after the POST and the system starts booting that anything you have done within EasyBCD can have an effect on the system. Also as stated, it is only a graphical way to work with the BCD. So it could easily be the install of Android on your system, an OS that is not fully operational with PC's and is only ported and a Beta that could have caused this issue more so than our software.
As you state in your final paragraph, XP uses the boot.ini files, it does not use the BCD as that was created after XP. You will have to install EasyBCD in order to get the boot working properly from within XP.