Incremental back ups to external hard drive and importing to new computer

Question

I need some clarification on precisely how to back up additional pictures on a PC to an external hard drive to keep all the pictures in the same catalog and folder structure.I have exported my existing catalog (exporting the negative files and including the previews) to an EHD to a folder I have created called My lightroom Photos.Within this folder there are three sub-folders:(1)My Lightroom Photos previews.irdata, (2) My Lightroom Photos.lrcat LRCAT file and (3) Pictures (which contain copies of all the subject folders I have created on import-the original pictures being retained on the computer hard drive). When LR opens you have the option of backing up the alterations to pictures in an EHD (but not the pictures themselves).So if some alterations in the develop module are made,these are backed up as a fourth sub- folder on the EHD with the date recorded.However,if certain pictures are added to Lightroom following the earlier catalog export, how can these pictures together with the alterations be added to that same exported catalog with pictures added to various established folder names -eg France, Italy etc? LR is currently set to back up to the parent folder-My Lightroom Photos.
Secondly, I believe that to import the catalog into LR on a second computer,all that is necessary is direct LR to open the last dated LRCAT file from My Lightroom Photos folder on the EHD.However,my last backed up "fourth" LR folder only imported two grayed out images with no previews visible.
Any advice would be appreciated.

Answer 1

I assume that what you really need is some form of keeping the photograph folders on your internal hard drive in sync with the folders on your external hard drive (the catalog itself can be backed up from within Lightroom). This downloadable little utility works for me when I want to keep my spreadsheets, letters, iTunes files ...etc... backed up;
http://www.goodsync.com/download/update
It's nothing to do with Lightroom. You first set up simple jobs within the utility, telling it which folders on your internal drive should be backed up to which folders on your external drive. It will then run, and copy to the ehd any items in the source folder that have changed since the last sync. Then, if your internal hard drive fails, you can copy these folders and catalogs from your ehd to the replacement hd, using the original folder structure.
In Lightroom, the catalog is the main organisational tool, rather than the folder. I let LR decide on it's own folder structure, because I never refer to my RAW files outside of LR. Hope this helps.