You can only convert the organizer catalogs to LR, not the other way round.
If you write your metadata to tags in LR before importing in the organizer, you'll recover them. Collections will be translated into albums.
You might install a free 30 days trial version of PSE and install a small LR catalog to test how it works.
You mentioned not only tags, but also edits.
If you have set LR to write the edits in xmp sidecar files, those will be read by the ACR module of Elements. The richer features of LR and the full Photoshop ACR will be also taken into account, even if PSE can't change/edit them.
So, you should not need to create edited non raw versions in LR before importing as you probably would when importing eited raw files from another software. You can test if I am right from a trial version of PSE, but maybe you are already using PSE as an editor from LR?