Besides the indentation issue that @Werner described, the other placement issues can be understood with thinking in boxes as that is how TeX works.
Consider the following, where the TeX code is on the left and the output on the right.
Note that the first two cases produce identical output as the new line is taken to be a separation between a word, and each word is considered as a box. In the third case, the blank line in between indicates a new paragraph so each word (box) is placed on a new line.

Now consider your case with text and tables, and think of the table as being placed in a box. So Some text here. is treated similar to the AA in the above example, the table is treated as BB, and the subsequent text Some more text here. is treated as CC.
So, the output of the first example below is similar to the output of the first two examples above where each box is placed next to each other, and the second example below is comparable to the last case above where each box is treated as a new paragraph and placed on its own line.

\documentclass{article}
\usepackage{xcolor}
\usepackage{showexpl}
\lstdefinestyle{demoLatexStyle}{
basicstyle=\small\ttfamily,
numbers=left, numberstyle=\tiny, stepnumber=2, numbersep=5pt,
frame=none,
backgroundcolor=\color{yellow},
pos=r
}
\lstloadlanguages{[LaTeX]TeX}
\begin{document}
\begin{LTXexample}[style=demoLatexStyle]
AA
BB
CC
\end{LTXexample}
\begin{LTXexample}[style=demoLatexStyle]
AA BB CC
\end{LTXexample}
\begin{LTXexample}[style=demoLatexStyle]
AA
BB
CC
\end{LTXexample}
\begin{LTXexample}[style=demoLatexStyle]
Some text here.
\begin{tabular}{ l l }
a & b \\
c & d \\
\end{tabular}
Some more text here.
\end{LTXexample}
\begin{LTXexample}[style=demoLatexStyle]
Some text here.
\begin{tabular}{ l l }
a & b \\
c & d \\
\end{tabular}
Some more text here.
\end{LTXexample}
\end{document}
\hfillrather than a blank line, which would make the following text the same para as the tabular, so naturally affected by its width. – David Carlisle Feb 24 '12 at 20:46\hfillhas no visible effect except for adding some space between the table and the text. Even when I remove it, the last paragraph is still affected by the table. – Zifre Feb 24 '12 at 20:49