Natha Sampradaya Acknowledges Dwaita-Advaita Vilakshana Vada. It is both Dvaita and Advaita. At absolute level it recognises formless, nameless thing as Absolute truth which is called by the name Para Shiva. The Absolute level is described as:
अनामेति स्वयंमनादि सिद्धमेकमेवानादिनिधनं सिद्धसिद्धान्तप्रसिद्धं तस्येच्छामात्राधर्माधर्मिणी निजा शक्तिः प्रसिद्धा...
Actually for a Vaishnava it's better to go for a Vaishnava Guru. And, the same for others.
Quoting Lord Shiva's words from the KulAchudAmani Tantram:
UdAsino hyudAsinAm vanastha vanavAsinah | YatinAncha yatih prokta
grihasthAnam gurugrihi || Vaishnave vaishnavo grAhyo shaive
shaivasthApunah | ShAktike vidyAd dikshAswAmi na samshayah ||
Dhuni is basically a sacred fire burned in a site and a part of fire worship. In Nath tradition sadhus (celibate monks) in their later life settle at one place and ignite and worship sacred fire in the pit using various substances which is known as Dhuni.
As you have inquired this sacred Dhuni is not a simple burning of wood . In the Nath-Sampradaya ...