OS6 wondering

Hello, everybody!

This question is about ReadyNAS Ultra 4, Pro 4 and Pro 6 upgraded to OS6.

Some background:

I have been using RN104 and NV+ v1 for a few years now, but as time goes I realized that those machines are hopelessly outdated (NV+)/underpowered(RN104). As I had my backups on an ReadyNAS Ultra 6 which died on me I replaced it with a ReadyNAS Pro 6 - and at the same time did an upgrade from Radiator 4.x to OS6, to avoid problems with ssh. Now I have acquired a couple of Ultra 4 and a Pro4 to replace the RN104 and NV+. One of the machines was already having 2GB of memory and OS6, so I upgraded it to the latest version and the other ones got more memory and I upgraded myself. Smooth process no problems. Just downloading the files and following the procedures outlined in this forum.

The machines with OS6 seem to work well, maybe except the Pro6 that lost connection with the network once or twice a week. But scheduled power downs seem to have fixed the problem. So no concern here as of now.

...BUT...

...and here comes my wondering:

I tried to install a few apps on the newly converted machines, as well as on the machine that I bought with OS6 on it. Those were the apps available from OS6 GUI, like Shell-in-a-box, MySQL, SMB Plus and a couple of others. Unfortunately, most of them won't install. The GUI just says that the package cannot be installed and when I try to install it "manually" via ssh command line, I see that some package dependencies are not being satisfied. 

I have located the Debian distribution for x86 corresponding to the OS6 version and as I can see, at least some of the dependencies can be satisfied by installing the required packages. Afterwards I was able to install one of the apps that I could not install earlier. So now I am asking myself - and you guys:

1. is my approach correct or is there another way to do it? ...or did I mess up the installation of OS6 without knowing it?

2. is it OK to install the required packages and know I won't be breaking anything in the OS? As I am not a Linux guy I cannot tell what I will and will not be breaking. The thing that I am concerned about are - of course - the files in the disk array.

3. does anybody have a list of packages that are missing from OS6 as compared to the regular Debian distro? (If I recall the Debian might have been 8.11 jessie, but not entirely sure.)

Kind regards /ZJ