It's interesting to see how "kuenda losses the "ku", but becomes "nenda", not just "enda". Is there a rule to do that or is this just an irregular verb?
It's just irregular. The only irregular verbs I know of are kuwa and kuwa na which have irregular forms in the present tense. Kwenda and kwishi have their optional "kw-“ that can make them act like monosyllabic verbs, and then there are the irregular imperatives:
kwenda > nenda
kuja > njoo
kuleta > lete