Is your score positive? You win! (Some players win more than others.)
A woman needs a man like a fish needs a saxophone.
You only pay the culture point when first acquiring the card during a passage of time action. Just follow the text on the individual cards to determine when they can be used. Horsemanship Level 1 provides its benefit as long as you have the card - every turn. Weaving Level 1 gives you a one time bonus of an additional trade good - you don't get it every turn.
Although bear in mind that you have to have a Culture of at least X to use a level X Culture card.