As you have stated, you have stored the catalog in the external hard drive, you need to access the same catalog from the external hard drive on your desktop computer. You will be able to find all the changes and everything as you get it on the laptop.
You may also consider to get latest version of Lightroom with Creative cloud benefits providing you one its key feature, which is Lightroom Mobile.
You can do flagging, rating, editing etc on your mobile device.
Please click on the below link to check Lightroom mobile features and its usage.
Hope this helps.
Thanks for your reply. Maybe as I research the CC world I'll find what I want. But with LR4.4 - your solution doesn't address my problem. I realize I can access the catalog on the passport drive from my desktop and see everything as it looks from the laptop. But what I want is to move/copy the photos (all the changes, including history, flags and ratings) from the catalog on the passport drive to a different (larger) external drive plugged into my desktop. I want to access them from a different catalog, what I call my master cataglog. I basically want to use the laptop (and the catalog on the passport drive) as a temporary holding place while traveling. With 4.4 I know I can export them from the passport drive to the desktop drive but then I have to open the master catalog on the desktop and import the moved/copied files. Doing so will give me the photos as they last looked in the passport drive but it doesn't carry the history and, thus, the ability to go back to the originals. Additionally, it does not carry forward the flags / ratings. Again - maybe the cloud option (and maybe even LR 6) will give me that ability. If so - I'll bite the bullet but I'd rather not. I'd like to solve this problem without having to buy new software. And I really don't need to access the pics from my mobile device. I can see the appeal but it's not something I'd do.
You need to look into File > Import from Another Catalog. It brings your work in one catalogue into the one you're using.
There's a corresponding File > Export as Catalog command which creates a small catalogue of (say) a week's photos or a project. You can then take this with you.
Another thing to look at in more recent Lr versions is smart previews. So I can generate smart previews of 7000 pictures, copy my catalogue with them onto a portable drive, have a lot of editing capability before a trip, and then copy the catalogue back onto my main computer at the end.
john beardsworth has provided you with correct information to use the option Import from Another Catalog.
Please click on the below link for detailed information.
Hope this helps.
It does answer the question but it's still not exactly what I'd like. I provided most of what I want but in addition to working on photos while traveling, I also sometimes do volunteer work that allows me to work on photos away from home. What would be perfect would be an easier way to move just the photos I'm working on from one library to another - back and forth. Not the end of the world, and your comments have helped - just wishing the process was a tad friendlier.
Having said that - I appreciate both your and John's comments and help. Thank you very much.