Dear Wisdom Being,
Geshe Kelsang is not part of Shar Gaden. He has given them alot of help, advice and sponsorship, and stood up for the monks. The monks in india at Shar Gaden and Ser-pom have great respect for him. The Venerable abbot of Shar Gaden has known Geshe Kelsang for many many years.
The NKT is not part of the Gelugpa establishment but is Gelugpa, as it follows the pure lineage of Je Tsongkhapa.
Kind regards,
GR