I know that some here weigh the kittens regularly, but in my experiences, I never found that needed to be an issue. If they are not constantly crying for food, and if you see Mom is taking care of them and feeding them, and they are growing, I wouldn't worry about it.
Kittens are born different sizes and grow at different rates. There isn't one specific weight; if they they are constantly growing, that's what matters.
You will probably not see much at all in the way of pee or poop. Mom is stimulating them to go by licking them, and she cleans it by swallowing it (gross, I know, but it's a cat thing and to them it's not gross LOL). Shows she's being a good, attentive mother. Deja Vu was a really good mom, and I never saw a bit of it. They went right from that to the litter box.
It takes them a few weeks to get steady on their back legs. They will drag them for a while, and then for a while, while trying to learn to stand, will be wobbling and falling all over the place. You'll see them learning, and improving, little by little. If memory serves me correctly, they were close to 4 weeks before I really thought they were steady on their feet.
Their eyes usually open around 10-14 days.
It's normal for them to hang with Mom. And they should until their eyes open, when they begin to get more curious, and Mom will take more breaks. Most cats are very protective of their kittens, and it is my belief that they should not be taken or handled much away from their Mom until at least their eyes open. If Mom is uncomfortable about that, respect it. After all, they are her kittens.
Deja Vu was very generous with her kittens, but I still would not handle them much. The only time I took them out was once a day to change the layer of paper towels, and then I waited for Mom to go eat or use the litterbox, just put them on a towel right outside their box, changed the towels, and put them right back in.
Not that I didn't enjoy them. I would lay there with them and talk to them all the time. I would use one finger to gently pet their little heads or bellies or sides. Since there were two that sometimes had trouble getting to their nipple (there were 5 of them) I'd sometimes use my finger to gently guide the side of their head over to where their usual nipple was. Once they felt it, they grabbed on and were home!
Once the open their eyes, you'll find Mom is leaving them alone more and will most likely be much more willing to let you play with them, take them out, have all kinds of fun with them. Also regarding pictures, I only took them while they were in the box, and usually while nursing, and when there was enough natural light. While their eyes are still closed they are still developing, and the harsh light can hurt their little eyes through the membranes. Again, once their eyes open, that's when you can really begin to enjoy them. And when they will become more friendly and curious, playful and mischievious.
Watch the Mom for signs. Soon she'll start spending more and more time out of the box, and that's when you know its a good time to begin making friends.
If you're conerned that not handling them that much or picking them up at the beginning will keep them from bonding with people, for the record, I've been through this twice, once with 6 kittens, this last time with 5. Both times I've gotten feedback from the homes they went to, and compliments from the rescue group regarding not only the health, but the friendliness, temperament and how good they were with people.
I spoke to someone just about 3 weeks ago from the rescue about Deja Vu's kittens. She told me that the minute anyone walked by, all 4 of them were jumping up and down and meowing for attention as if to say, "pick me ujp, pic me up, me me me me me." All were almost immediatley adopted. One even by a vet's daughter, who could pretty much have their pick of the best kittens from a lot of places. One from the 1st litter I cared for the vet's assistant at the time took one the minute she saw them, and one went to a severely depressed woman who had suffered many losses. I got a call from the daughter of the woman who told me the kitten was so attentive and loving to her mother, that she had done a 100% turnaround and they were considering taking her off meds.
So, for what it's worth, I must be doing something right.
In fact, I honestly think that by handling them and taking them away too early, they get more nervous. By waiting (and as I said, I did spend time talking to them from day 1, petting them, watching over them, helping if needed) they were more secure and less afraid, at least that's my opinion.
I'm sure you'll hear others, we are all different. But I wish you luck, and hope they are all happy, healthy, and wherever they go, always loved and wanted.