citations not rendering correctly with biblatex

Question

Citations aren't rendering properly with brackets around the year for $\cite{}\ and $\citep{}$ is throwing Undefined control sequence errors. How do I get this to work and format correctly?

\documentclass{paper} 
\usepackage[style=authoryear]{biblatex}
\addbibresource{bibliog.bib}

\begin{document}

This should be Giorgi (2002): \cite{Giorgi:WsBBLFIL}\\
This should be (Giorgi 2002): \citep{Giorgi:WsBBLFIL}\\
This should be (Giorgi 2002, Blodgett et al. 2008): \citep{Giorgi:WsBBLFIL,Blodgett:2008jg}\\
This is a book: \citep{Glesne:r1QiTFGB}

\printbibliography    
\end{document}

bibliog.bib

@article{Giorgi:WsBBLFIL,
author = {Giorgi, Amedeo},
title = {{The Question of Validity in Qualitative Research}},
journal = {Journal of Phenomenological Psychology},
year = {2002},
volume = {33},
number = {1},
pages = {1--18},
month = mar
}

@article{Blodgett:2008jg,
author = {Blodgett, Jeffrey G and Bakir, Aysen and Rose, Gregory M},
title = {{A test of the validity of Hofstede's cultural framework}},
journal = {Journal of Consumer Marketing},
year = {2008},
volume = {25},
number = {6},
pages = {339--349},
month = sep
}

@book{Glesne:r1QiTFGB,
author = {Glesne, Corrine and Peshkin, Alan},
title = {{Becoming qualitative researchers : an introduction}},
publisher = {White Plains, N.Y. : Longman},
year = {1992}
}

Answer 1

Apparently this fits your requirements:

From the biblatex manual: "These (the \cite and \Cite commands) are the bare citation commands. They print the citation without any additions such as parentheses", so you should probably use \citet.

To change the name-year delimiter, you have to redefine \nameyeardelim:

\DeclareDelimFormat{nameyeardelim}{\addspace}

and to change the multi-author separator, redefine \multicitedelim:

\renewcommand*{\multicitedelim}{\addcomma\space}

and it should work.

\RequirePackage{filecontents}
\begin{filecontents}{bibliog.bib}
@article{Giorgi:WsBBLFIL,
author = {Giorgi, Amedeo},
title = {{The Question of Validity in Qualitative Research}},
journal = {Journal of Phenomenological Psychology},
year = {2002},
volume = {33},
number = {1},
pages = {1--18},
month = mar
}

@article{Blodgett:2008jg,
author = {Blodgett, Jeffrey G and Bakir, Aysen and Rose, Gregory M},
title = {{A test of the validity of Hofstede's cultural framework}},
journal = {Journal of Consumer Marketing},
year = {2008},
volume = {25},
number = {6},
pages = {339--349},
month = sep
}

@book{Glesne:r1QiTFGB,
author = {Glesne, Corrine and Peshkin, Alan},
title = {{Becoming qualitative researchers : an introduction}},
publisher = {White Plains, N.Y. : Longman},
year = {1992}
}
\end{filecontents}
\documentclass{paper} 
\usepackage[style=authoryear,natbib=true,citestyle=authoryear,maxcitenames=2]{biblatex}
\addbibresource{bibliog.bib}

\DeclareDelimFormat{nameyeardelim}{\addspace}
\renewcommand*{\multicitedelim}{\addcomma\space}

\begin{document}

This should be Giorgi (2002): \citet{Giorgi:WsBBLFIL}\\
This should be (Giorgi 2002): \citep{Giorgi:WsBBLFIL}\\
This should be (Giorgi 2002, Blodgett et al. 2008): \citep{Giorgi:WsBBLFIL,Blodgett:2008jg}\\
This is a book: \citep{Glesne:r1QiTFGB}

\printbibliography
\end{document}

Answer 2

As suggested in comments, natbib=true enables use of natbib citation commands. This code also demonstrates how to use Biblatex's own commands to achieve the same results.

\textcite and \autocite are style-dependent. So if you need something other than authoryear, the format will adapt accordingly. \parencite is less logical, more appearance markup.

I've also adjusted the punctuation and number of names used in citation labels. In addition, I've corrected the .bib file. Although the problems here did not cause any issues you asked about, they did cause some inconsistencies and would cause problems in other cases.

\begin{filecontents}{\jobname1.bib}
@article{Giorgi:WsBBLFIL,
author = {Giorgi, Amedeo},
title = {The Question of Validity in Qualitative Research},
journal = {Journal of Phenomenological Psychology},
year = {2002},
volume = {33},
number = {1},
pages = {1--18},
month = mar
}

@article{Blodgett:2008jg,
author = {Blodgett, Jeffrey G and Bakir, Aysen and Rose, Gregory M},
title = {A Test of the Validity of {Hofstede}'s Cultural Framework},
journal = {Journal of Consumer Marketing},
year = {2008},
volume = {25},
number = {6},
pages = {339--349},
month = sep
}

@book{Glesne:r1QiTFGB,
author = {Glesne, Corrine and Peshkin, Alan},
title = {Becoming Qualitative Researchers: An Introduction},
address = {White Plains, N.Y.},
publisher= {Longman},
year = {1992}
}
\end{filecontents}

\documentclass{paper} 
\usepackage[style=authoryear,natbib=true,maxcitenames=1]{biblatex}
\addbibresource{\jobname1.bib}
\renewcommand*{\multicitedelim}{\addcomma\space}% corrected in light of moewe's comment
\DeclareDelimFormat{nameyeardelim}{\space}
\begin{document}

This should be Giorgi (2002): \textcite{Giorgi:WsBBLFIL}\\
This should be (Giorgi 2002): \autocite{Giorgi:WsBBLFIL}, \parencite{Giorgi:WsBBLFIL} or, with the \verb|natbib=true| option, \citep{Giorgi:WsBBLFIL}\\
This should be (Giorgi 2002, Blodgett et al. 2008): \citep{Giorgi:WsBBLFIL,Blodgett:2008jg}\\
This is a book: \citep{Glesne:r1QiTFGB}

\printbibliography    
\end{document}