Are there any update about a first release ?
I'm planning an initial release a week before Christmas.
I would like to know if the FBA and mame core will have the ability to display games by their long name (using some kind of DAT or rom list) or only by the name of the zip.
Not yet in the initial release. I'm planning to integrate RetroLaunch (which has the ability to do something like that) into mainline in future releases.
I see that mame core is based on 0.78 wich is probably a good compromise between speed and functionality (save states support).
If we go any lower we'll sacrifice compatibility (well, MAME 0.72 is still a good balance - I could create a separate version for mame 0.72 if it's worthwhile and if there's a big speed difference between 0.72 and 0.78) - if we go any higher we'll sacrifice speed, so yes, pick and choosing a good version of MAME for slower systems (ARM, PS3, 360) is like being stuck between a rock and a hard place.
Currently the most outstanding issues in MAME are to do with this being a legacy codebase - out-of-sequency memory reading is an issue (I suspect this is what is behind the massive problems I've been having with the Midway drivers on PS3), there are some 64bit bugs still in here (this will not affect Android though as every architecture on Android is 32bit - but it does affect PC), endian isues, and other issues of the sort. I'm still hoping some people familiar with this codebase can help me out based on their past experiences with it.
Are you going to use only one frontend for all the cores or one frontend per system ?
The initial release will just have one frontend - anyway, anybody can feel free to design their own frontends - I've designed RetroArch Android in such a way that the entire program is still C (as a native activity library) but the frontend is all Java (which is totally separate from RetroArch itself) - so everyone with basically zero to no coding skills could knock up a frontend themselves if they don't like the initial one I'll be supplying.
Will it be possible to map keys to physical buttons ?
If by pressing it it sends an Android key code, then yes,it will be supported - basically, Android works in a way so that it translates Linux keycodes into Android key codes through some Java event service. So I'd expect your physical buttons to be supported yes.