Do the seedlings look healthy ?

Transplant into some soil. Seedlings look fine for the most part.
First seedling looks mutated.

whats the cause of the mutation ?
and should i transplant them now ? I am quite busy for some days, can i transplant them after a week ?

jsut keep watering/feeding and they should make it a week.

Do they need feeding now ? they're only a few days old right now..
and i'm thinking of transplanting them into some good potting soil then i'll use urine as fertilizer.

Is that coco? Your biggest problem now will be over watering and over feeding. Here is how I do this.

I make up a light plant food maybe only 100 ppm, 16-16-16 and after I rinsed the coir with 4x vol. of RO to get the salt out, I do a final rise with the plant food.

I start seedlings in 1/2 that amount. Very important to not have a lot of water to access. We want those roots to get slowly thirsty over the next week and pretty much run out of water.

Then go to that size for a week or so, and then into a 6 inch azalea pot. Azalea gets transplanted a lot at first, so those pot have very slanted sides. So, now maybe I am 1 month in, have grown a good root ball that can withstand daily feeding.

Then they go into 50/50 coir and hydroton in a 2.5 gal rose bucket and that is it for the next 3 months till harvest. No more transplanting. I just move the buckets across 4 different feeding station (always the same food, different ppm, and two lighting area.

HTH... All in my journal, btw.

Are those is beach sand?

that is my normal garden soil.
I'll buy some good soil soon and will transplant them into better pots.
I don't water them so much, i watered them today after 1 week.
I'll be feeding them next week, i will use urine.
is it ok to use urine , 1:15 ratio or i should use organic fertilizer. I don't want to use chemicals.
Its India(rajasthani) soil.

Actual urine? I don't know. Uncle Ben may. Urea nitrogen, I will use at first to get them kicked started if needs be. So, I spray a bit a diluted lawn food.

It is an interesting question. And as this is more Botany Lab than help desk, maybe you could google urine as plant food and let us know.

It sounds like a good idea.

1:15 urine-water ration is good for starting and slowly decrease the amount of water until 1:10,
you can eat multi vitamins 3 hours before peeing as only 15% nutrients are absorbed by our body and rest are thrown out in excreta.

Ah..good to know.