Does the hadith "Whoever loves a people will be resurrected with them" apply to expressing love for a kind-hearted Christian colleague, with the intention of not remaining with her in the Hereafter? And what are the limits of interaction and emotions towards Christian female colleagues?

There is a difference in the ruling between loving a disbeliever for their false religion, and loving them for a specific reason such as kinship, marriage, or dealings, or for the knowledge or benefit they offer to people. This latter type of love is not forbidden and does not contradict hating them in religion and disavowing their disbelief.