To eliminate porn results, go tools > options > filters > keywords. Tick 'ignore adult content' > apply. You can also add specific words to the keyword filter if you want.
Before downloading a file, right click > look up file with Bitzi. If the file's been rated, you'll get an idea of it's content & quality. If a file's not rated but you want to take a chance on it anyway, preview after about 10% download. Then you'll see what you're getting & can kill the download if it's not a good file!

For the blank screen issue, did you go through those links that I left in one of your other posts? You could also try deleting your preferences folder when LW's closed, see points 2 & 3 here
Fixes for LimeWire
Have you tried updating your Java? There's a link above for that too
*Deleting the prefs will kill all of your settings within options. You'll have to go back through & reset things afterwards.