Here are the patches. Each patch corresponds to one of the headings in 
the original email. Hopefully they're fairly self-explanatory since I've 
added documentation to the manual as well as NEWS entries for each. I 
debated whether these should count as incompatible changes, but for most 
cases, I think there shouldn't be any incompatibility.

The highest-risk patch is the second one, since it converts multi-line 
numeric output from subcommands into a list of numbers. However, this 
helps a lot in fixing some of the problems in the third issue 
(concatenating expansions), and I think it's more consistent overall 
than before. However, it could make sense to provide a defcustom to opt 
out of the behavior if people think that would be helpful.