[littlehamster]

Tongue kissing can happen anytime, generally during foreplay to get her into the mood quickly, or even to help her reach orgasm. Or after she's had an orgasm, once you're both exhausted from intercourse, you can end with tongue kissing - that works too.
For many women, clitoral pleasure is more direct than deeper vaginal stimulation. The clitoris is the most important erogenous zone, and that's really important. Everything below there can make her feel good, but the clitoris is especially sensitive - you really need to stimulate it.