LR4 importing files
A few basic q's about LR if you don't mind to get me started on the right track...
I recently upgraded my dated XP desktop to a decent spec windows 7 laptop and have purchased a copy of LR4. Over the last 10 years I have amassed approx 20,000 pictures, some good, most terrible but all with keep sake value. To date I've only really used Picassa to manage my pictures which was good as it auto scanned directories on launch making life very easy but since getting into m43 and developing my photography I have been finding it very limited, so when my new laptop arrived I instantly bought a copy of LR4.
To begin with, I copied all my existing photos/folders into 'my pictures' on the new laptop, loaded LR4 and imported the 'my pictures' folder. It took hours to scan all my pictures but once complete I realised my folder structure was appalling and I ended up going back into 'my pictures' folder and deleting, moving and reorganising new folders and organising them more logically. However, when finished I was surprised LR didn't automatically recognise these change and inserted question marks where the folder/files were previously to be located? The only way I could find to rectify this was to remove my pictures folder from LR and re-import the entire folder taking hours again to rescan directory and individual files. Is there an easier way? Can LR auto detect changes made in 'my pictures' folder every time its launched?
Also, should I convert my files to DNG format on import or or just use Add option?
Whats the best way to import pictures? Direct from SD or separately into my pictures prior to loading up LR?