I haven't messed around much with OEM's myself, but the only thing to keep in mind is that if you shift a package from there to the EXT, you need to convert it to EXT format. Change .rgu's to app.reg files, delete the .dsm's, and get the proper folder structure. Once, I moved NETCF from a Sys to my EXT directory, not thinking about the folder conversion, and I ended up with a rom that didn't have net framework. It booted up ok, but let me tell you, that rom suck hard. It took me a while to figure out what I'd done wrong. Check your dump before flashing just to make sure all the files are included.
Random Access is the alphabet that appears on the right side of your contacts (and other places), and that gives you a quick shortcut to hop down to a specific letter. I'm guessing irsir.dll is some IR based driver? But if it's in your oem, then maybe it's something else. A quick google will definitely tell you what it is.
Edit: yeah irsir.dll is an ir driver
Fast IR Driver nscirda.dll
Serial IR Driver Irsir.dll
Here's a thread
that says you can remove irsir.dll if you don't have IR on your device. Not sure why they put it in, in that case.