alejandro,
Being in Puerto Rico, something's may be different for you there than us in the US or Australia.
Here we use Paper towels or newspaper for small babies as they are more prone to impactions from sand, dirt, bed a beast, calci-sand and other substrates that do not digest. Your doing fine with the newspaper. Later you can add an area of washed playsand (fine grain) but still try not to feed him on it.
Baby dragons will eat salad (recommended rich greens like collards, mustard, dandelion and very little romaine or lettuce as they contain almost no nutrient value) happily if it is introduced to them when younger and it is a great source of many vitamins and minerals which they do need. If he will only eat crickets, you can dust those with Calcium a few times a week and also some vitamins. Some are hard to get started eating greens and veggies( yellow squash, carrot, sweet potatoes, green beans, green peppers and peas grated up fine) if they never had them, but as they grow older it will be a major part of their daily diet and they taper off the crickets and supersworms (worms for older dragons, not recommended for babies).
Although some dragons do come from the desert type area, they are also from lake regions, rain corridor and grasslands. Many become very fond of water and swimming. From a study we did in cooperation with vets form herpvetconnection, we found the leading cause of death and illness in baby dragons was dehydration, followed by parasites and then impactions. So you are very smart to already be concerned about those things and looks like you have done some studying up on them.
Your baby is very young and in the US we encourage people not to sell them under 6 weeks of age, as they are very fragile when younger. So you will have to be extra careful in his care and feedings and handling
Temps 95-105F are ideal, just make sure the baby has an area that is cooler that he can move to so he can regulate his own temps and not dehydrate.
He will also need a UVB light source like natural sun a few hours a day, or a UVB bulb or at minimum calcium with D3 (I do not think this is the best for them, but better than nothing). Bearded dragons need calcium to grown healthy and strong and they absorb that from their food by using UVB in lights or the sun to create pre D3 in their skin. Without that, they baby will suffer and show signs of problems fairly quick.
Just avoid high oxalate foods like spinach, broccoli, cabbage and others as this tend to bind the absorption of calcium and that defeats the goal you want for him.
Let us know how he is doing and don't be afraid to ask anything, we all had to learn starting out and still are.
