In Roman Catholicism, I understand that as per traditions, while praying for the salvation of departed souls, we usually have to recite “Our father and hail Mary”. Is there any Church guidelines in this regards? There is some confusion as to whether we should conclude this with “Glory to the Father and the Son ....” or not. Either way what is the significance of concluding it with or without "Glory to...." in the end?
I think there's two questions here:
The "Glory to the Father" prayer is a doxology and is a traditional way to end a prayer or series of prayers. It's prayed at the end of each decade of the Rosary and at the end of each psalm in a psalter such as the Liturgy of the Hours.
A pious custom is to recite 3 Hail Mary's, 3 Our Father's and 3 Glory Be's when visiting a church. I believe that constitutes a partial indulgence (under the normal criteria), which is a good and easy way to get an indulgence every day.
Even though it's not the norm for the Church any more, the Raccolta is chuck full of different prayers that could be prayed to receive indulgences and those indulgences can be applied to a holy soul in purgatory.
So, I think you do need to pray a Glory Be prayer, if that indulgence is specifically what you're going for.
Various specific prayers have, as Peter Turner explained, indulgences attached to them, and various prayers have become customary in praying for the dead, but there's nothing to prevent a Catholic from praying for the dead (or for any other purpose) in whatever words he wants. I often say a very brief prayer of the form "Father, please bring [name] to heaven soon if you didn't already." There's probably no indulgence attached, but I'm sure God pays attention, as He does to everything we say or do.