Lichtenberg FTW! These words of his are quoted in a great article:

Helbig, Daniela K. (2019) Ruminant machines: a twentieth century episode in the material history of ideas. JHI Blog April 17, 2019. https://jhiblog.org/2019/04/17/ruminant-machines-a-twentieth-century-episode-in-the-material-history-of-ideas/

Also quoted there is a comment of Lichtenberg’s that shows the great value of the Zettelkasten technique in connecting disparate ideas. Unfortunately for him, using notebooks the way he did, Lichtenberg found it hard to link his ideas in the way he desired:

“Oh how many ideas aren’t hovering dispersed in my head! Quite a few pairs among those could provoke the greatest discovery if only they came together. But isolated from one another they lie, just like the sulphur from the city of Goslar lies isolated from East Indian nitre and from Oaksfield coal dust when jointly they could produce gunpowder!”

Fortunately for us, we can read for ourselves the digitised versions of Lichtenberg’s wastebooks.

Each page just has a page number at the top corner, as far as I can see. The German Wikipedia entry says that from notebook E, he numbered the front pages with Arabic numerals and the back pages with Roman numerals, so his notes began at both ends and met in the middle of the book. This is clear in the original, but hard to understand. And he would at least have been able to refer to his notes in the form {volume letter, page number}.

It seems he didn’t number consecutive entries himself, but that in later Lichtenberg scholarship there developed an editorial convention to do so. After his death they only published his ‘aphorisms’, organised by theme, and later re-organised by date, but still missing his scientific and other writings.

Also, I haven’t found an index, much less one that echoes the methods of John Locke. Would be interested to see such a thing though, if it does exist. The evidence of the Wastebooks suggests that if he knew about Locke’s methods (and he was an Anglophile), he ignored them.

Analysis of Lichtenberg’s methods is in: McGillen, P. Wit, bookishness, and the epistemic impact of note-taking:. Dtsch Vierteljahrsschr Literaturwiss Geistesgesch 90, 501–528 (2016). https://doi.org/10.1007/s41245-016-0025-8

Possible further answers to your open questions are in »›Schmierbuchmethode bestens zu empfehlen.‹ Sudelbücher?«, in: Ulrich Joost et al. (eds.), Georg Christoph Lichtenberg 1742–1799. Wagnis der Aufklärung, München 1992, 19–48. PDF in German

There’s plenty more at the Lichtenberg society.

And a fascinating online exhibition. See display no. 20 for an example of one of Lichtenberg’s annotated bibliographies, which he had published specially in an interleaved edition, and, wouldn’t you know it, some of his loose slips!