[Windows Mobile] KilZone:
There are no dumb* questions! Feel free to ask anything you want to know...

Whenever HTC releases a new device, it will come with a new version of for example Manila or any other package (CommManager, Notification Enhancement, etc.). Because 'modules' are faster than the normal 'files', HTC consistently prefers these 'modules' over the 'files' and thus will release newer software with more modules than the previous version. However (older) devices can support only up to a certain number of modules before 'overloading'... Furthermore, some older devices cannot support the new modules. (For example 'config.dll' in Notification Enhancement as module will crash most older devices, like mine.) The kitchen will automatically alert you if you have those packages (not working ones) in the list and ask you to recmod them. Best answer (if you don't want to do it manually) is to say 'Yes'. However know that (in case of Noticition Enhancement) it will RecMod all modules in the EXT Package, where it might be possible to alter just one module. (So ease of use will come at a little price of speed when operating your device. Only option is to do everything by hand and alter files yourself, it will be a lot of trial and error though.)

FileSystem Cache and PagePool is different for all devices you want to cook for. The more RAM a device has, the larger the PagePool can be without interfering with normal operations. I right now use (for BlackStone) 16MB or 18MB depending on the WinMo build. However this is something you will have to find out by yourself. Basically it is like this: The larger your PagePool the faster the device, but the less RAM you have available for normal operations. You will have to find the acceptable level for your device.

FileSystem Cache is a little more consistent but will require trial-and-error nonetheless. Mostly around 4MB (4096) will be enough, but you might find it better to use 2 or 8 for example...

The IMGFS Reserved Space is the update space your ROM has when flashed to a device. WinMo has the ability to update the ROM Over-The-Air (OTA) like any other Mobile OS, but does require atleast some 'IMGFS Reserved Space' to do so. If you want to release ROM updates for your ROM you will have to include something (not sure how much) but if you will not provide ROM updates, best to remove it completely (0mb). Remember: ROM updates are different from CAB updates! A ROM update will update files in the ROM, so that after Hard Reset it will still be installed, where a CAB update will simply overwrite the file and be removed after Hard Reset. (The last one is the easiest to make...)

The SYS is part of Windows Mobile yes, but the XIP is not completely made by Microsoft. There are 2 parts, OEMXIPKernel and MSXIPKernel. The first is made by HTC, the second by Microsoft. The OEMXIPKernel is device specific, the Microsoft one is not. Custom XIPs (combinations of different OEMXIPKernels or MSXIPKernels) can increase device performance, but comes at risk of damaging your device. My advice is to leave this as is and just use the dumped OEMXIPKernel and the MSXIPKernel that comes with the WinMo Build.

Short answer: NO! The ROM building process is completely automated. You can use these events to (for example) compress all PNG images in your ROM or to alter the generated ROM, whatever. If you cannot think of a reason why you really require one of these events, don't use them (yet).

Hope that helped!

* The only 'dumb' question is one that has already been answered