As regards Pradakshinam, it is appeared to have various reasons for doing it. During the
Pradosham day (first time) Sutra Pradakshinam, is the suggested way of circumambulating
the God. In some temples, this is generally followed. What I want to mention here is a
point about the practices adopted. When they do Pradakshina, the go upto Gomukhi and
it is not crossed. We all know that is the point where the Abisheka Tirtam flows through
the Gomukhi, generally towards northwards. By doing this way of Pradakshinam, one
does not cross over the holy water that passes through the Gomukhi. The Pradakshinam
is done like that above.
Now starting from the base point of Nandi (Rishabar), we call it as Holy Bull, saluting him
go anti-clockwise and Salute the Chandikeswarar (not crossing the Gomukhi). After that
return clock-wise and Salute Nandi Bhagwan and continue the Pradakshinam clockwise
till the Gomukhi, without crossing it. After this, return in anti-clockwise direction, salute
Nandi Bhagwan again and proceeds towards the Chandikeswarar. From there, now return
back clockwise without saluting the Nandi Bhagwan and reach the Gomukhi point. Finally
return back anti clockwise from Gomukhi to Salute Nandi Bhagwan and proceed towards
Chandikeswarar and come back to Nandi Bhagwan and stand by the side of him and
now offer the worship to Shiva Lingam i.e. Lord Shiva by viewing through the space
between the two Horns of Nandi Bhagwan i.e the Holy Bull. Now this is one Pradakshinam.
I have just seen a chart about this and reproduced the above from that. With the
above exercise, Three such Pradakshinams are to be done on the Pradosham Day.