Dont worry about semi bricks, they are fixable; if that happens just get into flash0 and replace your topmenu. Semibricks sound scary but this means an "RCO" is faulty so when your psp tries to "LOAD" the file the XMB will just freeze. Because the rco is bad. But nothing to worry about. But I understand your concern. Semibricks 'sucks'. Just giving out some of my thoughts
Yes, that will get rid of the shadow 100%.. Its gone.. Completely gone after.