1 and 3
In a way, questions 1 and 3 are the same, or they can at least be answered in the same way, which is that described in Translate paragraph environment.
In short, if you're using
babel, which I think is the default behaviour, go to Document --> Settings --> LaTeX preamble, and add
babel is turned off, you need just
In either case only the PDF will change, not the view in LyX.
(For the abstract, another way would be to 'cheat' a bit by using Quote instead of Abstract, and reducing the font size to Small.)
2 and 4
Question 2 and 4 are also sort of the same question, they are about formatting
article (which is the default document class used by LyX), the References-heading is an unnumbered section, so the same formatting applies.
The LaTeX answer can be found in the first part of the answer to \newcommand for centered \section, you just need to remove the
\bfseries, as you didn't want them to be bold. To apply this in LyX, again go to Document --> Settings --> LaTeX preamble and add