LaTeX.org

Maybe \alpha?

Double backslash and noindent is certainly wrong. Dunno what you are doing, but it can't be a solution.

Welcome to the forum,
i can reproduce your issue, but i currently have no idea why i is happening.

Have you thought about a slightly different table design? I guess the final result will be quite hard to read.

A longtable does not float, it appears in the pdf where you pit it in the source code.

Yes, makeglossaries.
What did the terminal output?

Welcome to the forum.

Have you run a program that takes care of the glossary stuff?

I cannot really tell.
Always try out the stuff with minimal examples and see what happens.

I didn't see a \bibliographystyle command in your very first posts, else i would have suggested a suitable biblatex style.

You need something like \bibliographystyle{apalike}

I don't know how you installed the package.
Depending on how far you are into your thesis, you could just update your whole tex distribution using the package manager, but it might lead to other incompatibilities.