It looks like your doing a good job so far to me ^_^ the first close up is a bit blurry but the kit has it right. Each thread should have six strands and then you use however many of those strands the kit calls for. I believe stamped ones ask for 3 but it could be 2. Haven't done one in awhile >.< .
Don't worry too much about there being spaces visible between your stitches. Just concentrate on keeping your stitches even and pulled snug against the fabric.
The instructions should tell you that you will need to wash this once you're finished and that will cause some shrinking which will in turn cause your stitches to look a little fuller. This is also why it's important to keep your stitches snug and not too tight/loose as it can make your thread get caught on things easily or become sunken into the fabric.
Like I said though, your piece is looking really nice so far ^_^ lol, It can cramp up your hand a bit though. I've been stitching for years and I still have this problem. Just make sure you take breaks when it does start to bother you and I find the massaging my hand some helps as well. After awhile those muscles shouldn't be too bothered as you get more practice in.
Keep at it and feel free to ask questions if you have any concerns here! ^_^ We're a friendly lot of people and shall be glad to offer advice.