It doesnt matter when you take creatine, it is build up in your muscles and works from there, hence the loading phase. U can even skip the loading phase, it will just take longer to work.
It does need a delivering mechanism, dextrose is perfect for this. I throw it in my post workout shake as I am already having a lot of dextrose in there to stop catabolism and help with delivering the aminos from the whey, now creatine is delivered as well.
Sweet stuff like dextrose or fructose spikes your blood glucose, which leads to your body secreting insulin to absorb this (normally turned to fat, and thats why chocolates are bad

) now you have creatine there as well, so the creatine is absorbed as well....
5 or 10 grams is fine, both are preached, it doesnt matter, u can only have a certain amount in your body, the rest is just not absorbed. And obviously it depends on how big u are and how hard u train. I aim for 10, but forget the second dose most of the time.