Transit through DEL T3.
 

Does transit through DEL, say XXX-DEL-KTM-DEL-XXX or XXX-DEL-CMB-DEl-XXX count as entry into India?

umm no. Not for the purposes of the 2 month rule.
you'd be in the international transit area but on indian ground.

none of these would require you to go through immigration so there would be no entry into the country....

If one were holding a valid Indian tourist visa and were to go through immigration at DEL for an overnight hotel stay on each of the two transits throught DEL then isn't there a waiver of the 2 month rule for exit to and re-entry from a few of the neighboring countries?

My daughter is flying ORD-DEL-DAC and returning within three weeks DAC-DEL-ORD and plans an overnight stay at the DEL Radisson on each of the two transits through DEL. Will she be better off getting a tourist visa or a transit visa holding a US passport? Are there multiple entry transit visas issued by the Indian Government?

SO your the date of your last departure from India has no bearing on your ability to transit through T3.

Kathmandu flights are considered domestic, or international? Do they depart from the international concourse?

nope....you are good as long as you don't clear immigration....

they are considered international & they depart from the international concourse....

Thank you Keyser.