Question: WHat is the purpose of the PDF files that includes just 1 image each in the zip file? Is PDF used as an image format for the images used by the emulator?

It's just the image format Apple likes the toolbar icons to be so that they scale better. My favourite is .png, which i've also tried, but the icons didn't look as good. I would prefer to put all them inside a single image-list bitmap .png, as we do in windows, but i've not found yet (didn't bother either) a way to do it.

ML is quite lazy to start-up, it takes ages when compared to good old SL (period).

I told you it was a monster. Lion was, but not as much.

Looks pretty nice

Probably since Mac OS X and iOS share a large part of their core libraries (namely Cocoa, which this app uses, and Cocoa touch). But :
1) I doubt it will be done before this port is finished.
2) It probably won't be accepted on the AppStore so you'll need to jailbreak.

Because Apple rules for apps are very strict and they most likely won't accept emulators because it opens a breach to run arbitrary stuff w/o jailbreaking (even if it's sandboxed).
Also, where did you get this pic from ?

... i would like to help making it for iOS.

Well, I guess the idea (iPad port) is somewhat attractive at first, but there are some difficulties along the way that would need to be tackled first:

1. We need to keep in mind that iPad and most of the Android devices are based on the ARM cpu and not on the x86 cpu for which nspire_emu is coded. Much of the nspire_emu memory access code is implemented in x86 assembly. So that, at least, would have to be re-written by someone with deep knowledge of both architectures. This fact poses not minor difficulties, as already mentioned by Goplat here: http://ourl.ca/9360/333346 and elsewhere on the net, e.g.: http://stackoverflow.com/questions/1732394/differences-between-arm-assembly-and-x86-assembly . Google <sometimes> is your friend.

2. Probably a first step towards that solution would consist on porting nspire_emu to an ARM cpu. I guess some 'windows8' implementations already run on top of ARM cpus but personally I'm not familiar with it.

3. So, I would suggest someone finds a window8 machine that runs on an ARM cpu and fiddles with the open-source nspire_emu code to try to port it. This step requires quite some assembly language expertise as said above.

4. Porting the GUI should not be much of a problem although it requires some time.

5. Last but not least, the AppleStore/GoogleStore stuff really sucks, IMO, but i guess we'll have to learn to live with it for a while…

Good Luck!

and fiddles with the open-source nspire_emu code to try to port it

The open-source nspire_emu code is indeed a better starting point for fiddling than your closed-source forks, because it's, well, open-source

5. Last but not least, the AppleStore/GoogleStore stuff really sucks, IMO, but i guess we'll have to learn to live with it for a while…

Some people thought that selling your closed-source forks on an app store was the motivation for making them closed-source... but it seems that they were wrong.

you can make apps free without adds and you have to pay $99 once a year.
there must be a way to get it in a legal way.. i hope.

but it must be programed  first...