2) Normally, even the characters are prerendered, but if you wanna use 3d characters, use .3ds-file format. It is an Max-export format and easy to read. You can find some information on www.wotsit.org .
3) You can use shadows in iso-engines without D3D, but the algorithms are mostly really complex. I guess Geoff wrote something about on www.lupinegames.com . I did never use lighting and things like that. But for example for a limited viewport, you need 2 different maps, one with the colored map and one monochrom one, and then simply use rays. This shouldn't be such a big problem, but it's slow, I guess. As I said, I never tried it out. I've seen some more article on this topic, but I'm not sure, maybe www.perplexed.com/GPMega/ ?
CU
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Skullpture Entertainment
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