Workflow to find/create subclips for use elsewhere, avoid modifying originals.

I have a library of original video footage from various cameras. I wish to establish a workflow that allows me to review all of the footage in that library, finding either entire clips, or subclips from entire clips, where I eventually copy/transcode those discovered clips/subclips to new copies for use in a new project. I want to avoid any modification whatsoever to the original source footage... the original source footage operating system "file modified time" should not change as a result of any operations in this workflow, including metadata changes.

All original footage is from consumer grade or DSLR cameras... it's either MOV, MTS, m2ts, wmv, mp4, etc. I wish to eventually get all discovered clips/subclips into 1080p, yet all clips may not have a matching dimension or even aspect ratio... that's fine... I don't mind black edges when a clip's width/height doesn't fit standard 1080p.

I looked at Prelude for a while, and while I like many of its features, I'm not certain it buys much for me when compared to using Premiere Pro directly for the above stage of the greater workflow.

When looking at Premiere Pro, I was thinking of ingesting without copying or transcoding, but with proxy creation, and working with proxies, but it's unclear that working with proxies guarantees Premiere will avoid any file modification to the originals such as metadata modifications (as one example) back to the original footage.

My current plan is to ensure the operating system Read Only attribute is active for all of the source footage in the original footage library. Unless Adobe does something totally unexpected (like modify file Read Only attributes without prompting me), that should be enough to prevent Prelude or Premiere or whatnot from successfully modifying the source files. After doing that, I'm thinking of ingesting with lower qual proxies and working against those copies, and finally exporting subclips.

It's unclear how to go about the entire process, or whether I should consider or avoid Prelude. I'm just going to try some things, such as the following...

1. Ingest into a Premiere Pro project all of the Read Only original footage with any copying/transcoding or proxy creation for the first pass (see next item).
2. With all clips loaded in the Premiere Pro project, take a first pass to find entire clips that have no value, delete them from the project.
3. With the remaining whole clips, create lower qual proxies for ease of use during the following steps...
4. Go back over all the remaining clips in the project and ... what? I'm guessing something like this: Identify entire original clips I want and move them to a "ForUse" Bin. For partial clips, create one or more subclips from the original, place them in the same "ForUse" Bin. The "ForUse" bin is then finally all of the footage I want to use, which may have some entire original clips or some partial subclips.
5. Transcode all of the "ForUse" clips/subclips from the original Read-Only footage to a nice intermediate codec copy such as DNxHD* and use those copies in the new project. Those new copies will be new assets that are owned by the new project, leaving the original footage untouched. The new project will have a good intermediate which should be close enough to the original for it to be good enough. (This is all amateur non-pro stuff... so "rough edges" should be fine.)

The above keeps the original footage left untouched. Will that workflow work well? Is there a better way? Should I consider any Prelude features? Am I way off here, is there a completely better way?

I'm sort of trying things out while asking this... forgive the abstract nature of the above but I'm sort of guessing at what will work as a way of asking my question... now I'm going to try that and check in here to see if someone says "stop, that's not what you want to do!" ... I'm in that time of flux when one is trying to figure out how to arrange all the pieces for an effective workflow.

This hardly seems unique to me... I'm guessing this is a well-solved workflow issue... original footage that should remain untouched, but from which one wants to get the best quality transcoded copies of entire or subclips from that original footage, all to create new assets to be used/maintained as part of a new project.

Thanks!