I have a reputation of 11 at the moment, but I have found a couple a very useful questions and answers, things I would like to up vote. If I do so now, it does not show up, but I believe it is stored. Does the person who posted the question/answer received reputation once my reputation is high enough for an up vote to count? Or, do I need to remember where I placed these votes and revisit them once my reputation is high enough and vote again?
Anonymous feedback (positive and negative) is in a different bin and affects things like placement on the home page, search results, etc.. but it doesn't grant direct reputation.
You can look at this help section to see how reputation works in specific.