I am new to lightroom cc. I don't have any idea the approx number of images I have but in terms of local hard drive space a rough guess is 100 GB max might be photos. I have 600 GB available hard drive space. Right now I have photos very disorganized all over the place and I would like to:
1. Clean them up and get rid of a lot of duplicates.
2. Organize them into collections within lightroom and apply metadata to them.
I know it will probably take a very long time, but is there any reason I can't just import the entire hard drive (or at least the main top level data folder)? It seems like it would make it so much easier to accomplish what I want if my folder structure in lightroom matches that on my computer, as opposed to having to import hundreds of different folders spread all over the place.
I don't think it matters if you import them all at once, or in batches. You can import the entire drive or the top folder.
You might want to consider importing via the COPY option, and then LR can place all of the photos (copies) in subfolders under a single parent folder. Do not set things up so that all 100 GB of photos is in a single folder with no subfolders.
When you do the organization inside of Lightroom, you want to use keywords and not collections. Keywords have more features and are viewable outside of Lightroom if you so choose.