3.27.3 Can you answer these questions?

Can you answer these?

3.27.3.1 pgfplotstable - combine two columns with LaTeX formating

https://tex.stackexchange.com/questions/385159/pgfplotstable-combine-two-columns-with-latex-formating

I'm trying to create new colMix column as two combined-columns from CSV file. Each of them may contain some (standard) LaTeX formating (included inside the CSV file). There is MWE (non-working): 
...
 

- asked by LuboAo\[DownExclamation] Kejzlar 2votes

3.27.3.2 arXiv's compilation introduces underfull \hboxes in bibliography due to hyperlinks

https://tex.stackexchange.com/questions/385499/arxivs-compilation-introduces-underfull-hboxes-in-bibliography-due-to-hyperlin

When I compile with MikTex on my computer, my bibliography compiles without issue: 
When arXiv compiles it, I get underfull hboxes such as 
The code for this citation: 
@article{Kogut:1974ag, 
...
 

- asked by zjw518 1vote

3.27.3.3 WordSpace= overridden by \spaceskip

https://tex.stackexchange.com/questions/385637/wordspace-overridden-by-spaceskip

In this example, the \spaceskip overrides the WordSpace option.  Why? 
\documentclass{article} 
\usepackage{fontspec} 
\spaceskip=.33333em plus .16667em  minus .125em 
...
 

- asked by Toothrot 1vote

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