1. After running ‘bibtex paper’, it reports

Too many commas in name 1 of "J.Chen, R.Monga, S.Bengio, R.Jozefowicz" for entry Revisit_SGD

This is because we need to use ‘and’ to replace commas. After changing them

# Change 'author = "J.Chen, R.Monga, S.Bengio, R.Jozefowicz"' to
author = "J.Chen and R.Monga and S.Bengio and R.Jozefowicz"

The errors disappeared.
2. How to extend space between two rows in a table?

\setlength{\tabcolsep}{10pt} % Default value: 6pt
\renewcommand{\arraystretch}{1.5} % Default value: 1
\begin{tabular}{ c c c }
First Row & -6 & -5 \\
Second Row & 4 & 10\\
Third Row & 20 & 30\\
Fourth Row & 100 & -30\\

3. Problem: Can’t upload .bib file in arXiv.org
Answer: run ‘pdflatex paper’ to generate paper.aux from paper.tex, and then run ‘bibtex paper’ to convert paper.bib to paper.bbl. Now we could upload .bbl file to arXiv.
4. Problem: When select ‘Tools’–>’Check Spelling…’ in texStudio, it report “No dictionary Available”.
Answer: Download english dictionary from https://extensions.openoffice.org/en/download/1471, change suffix from ‘oxt’ to ‘zip’ and unzip it. In ‘preferences’ of texStudio, set dictionary path to the unzip directory. (ref)
After solved all these problems, I eventually submit my paper here: https://arxiv.org/abs/1806.03925