It is a tradition to light lamps for Thirumalaiappan during Purattasi and many are following it. If there exists a tradition to light up lamps for Ranganathan, it can be done, but we are not aware of any. Should we follow that which is not in tradition just to prove our devotion?
Each one has different practices per their household, if the concerned house follows the tradition of lighting a lamp during Vaikuntha Ekadasi for Ranganathan, then do so otherwise do not start something new that is not ordained in tradition.
Gata deepam is one among several types of lamps that are offered as harathi to Perumal at temples. It is considered special as stated in Agamas. Both gatam and deepam are auspicious, when offered together it becomes more auspicious.
There is no need to use kumbha deepam during festive days, we can continue with agal deepam as per the usual practice. There is no need to do anything new.
Generally, one should not extinguish the lighted wick; but a tiered lamp gets blackened fast and after offering the tiered lamp to Perumal, we should take it out and extinguish the flame cautiously; it should not be done before Perumal and other onlookers.
Even now some temples follow the tradition of lighted lamps without interruption; akanda means uninterrupted; the lamps that are lit up uninterruptedly is called akanda deepam; Some house also practice this tradition, it is called ‘anaayaa vilakku’ in Tamil; One need not have a big lamp for lighting akanda deepam instead we can make sure the flame is always lit continuously.