I don't think that sand for an axolotl that small is the best idea, based on what I've heard. Sand can cause injury to the axolotl, especially if they eat some, and even more so when they are that small, so waiting until they are larger (probably at the very least 6 inches long) until doing sand is better. Even then, sand can be risky. I've heard that hand-feeding and/or providing a food dish is best if you choose to do sand.
As for food, I have my little guy eating frozen blood worms and night crawlers/earthworms and change which one i use every time I feed him. I had some problems with pellets and therefore I opt not to use them. However, many people do have good luck with pellets, so ask around and see what brands people use.
for an axolotl that size, I'd say that one to two pellets every three days is a reasonable amount. I feed mine at night since I've heard they're more active then. I generally wait until mine has pooped after eating before I feed again (usually 1-2 days) and he seems to be doing great.
hope this helps!