When one is with the Guru, and following the path, is it necessary even then to participate or conduct rituals?
If you have unshakeable faith on the Guru Tattva, then there is no need for anything else. But if you feel that you should perform certain rites and rituals, then that is fine too.
Also, doing anything without faith in the Guru Tattva, does not bring any benefits. Without the presence of the Guru, there will be no use of practicing any Tantra (an ancient school of spiritual practices) or mantras. And if you have surrendered yourself completely to the Guru, then there is little need for all these methods. But if you wish to practice that too, there is no problem in that.
For this, you have to find someone who can perform these rites and rituals correctly (as prescribed by the scriptures). And sometimes you should actually engage in some Karma Kaand (rituals and holy practices as mentioned in the scriptures) also; maybe once or twice a year. You need not over do them.
Do some puja, light a lamp before the deity at home once in a while, and sit silently in meditation sometimes. Meditation is the best among all practices.
If there is love, meditation and a sense of surrender, then everything else simply follows.
Sometimes, you may place a Toran (a traditional Indian door ornament believed to be auspicious and ward off ill omens) to decorate your doors in the house. That is the significance of the Toran. But if there are no doors, what is the point in placing a Toran then?