I don't understand php either, but you are among experts. I can read it a bit and know what is happening, on good days at least.
I think its like this, but I could be off. You're gonna have two chunks, no extra snippet as you have grabbed all the 'data' or 'items' in the snippet you do have. That's the php and we are just worried about the output.
If the data you are looking for is anywhere in that array of data, you've got it in memory and can output it.
Also watch out, I believe the placeholder for these values is one bracket, [+item], rather than two. Two brackets is Modx shorthand code, for chunks and snippets and other stuff too. [[$ChunkCall]] and [[!UncachedSnippetCall]]
Start with container and drill down
<p>[+total_count] and [+weight]</p>
and InnerChunkTpl contains something like
Now I beleive you can output all the data if you wish, when the snippet is grabbing just what you need and not necessarily everything in the json. That's an area I don't understand well but it looks a bit like this
and then all the values in the array will be listed.
Also, the first example of the page under Processing Chunk via the API might be useful for you, its a simple snippet and chunk for output, to get the list of resources