chan a.k.a nizam,

installation for cm7 is exactly same like MIUI.. here's the link to download those files
.. start from EZBase, then flash cm7 kernel without tick autoreboot, then reboot into CWM and flash cm7-initial-zip file..

There are 4 kernels for cm7 which are stock kernel, TK-Glitch, bilboa1 and platypus.. i've been using all kernels and i prefer platypus.. because you won't OC up to 1.5ghz will you? with platypus, you can UV up to -50mV on 1ghz and it's still stable ... I guess it depends on each device.. my phone can't do heavy UV.. very manja one 

1) probably its due to bootloader, did u flash from froyo or gb rom? im with miui, but if got the broken screen image, bootloader is the problem.

3) maybe there is something wrong with ur installation. ext sd if im not mistaken been fixed a long time ago.