Luggage and bags:
Unless you want to camp, take a backpack that would be small/big enough for one day trips. A world traveller like myself ;) came to El Chalten with the carry-on suitcase that was travelling with me around the country. It must have been a strange view for the real hikers. But I had my little backpack which was just perfect for a day trip. Other than that I still prefere a luggage with wheels over the one you have to carry on your back :)
Clothing/Shoes/Weather Gear: It's generally cold so both gloves and a cap came in handy when I was there in late summer. It came out the rain coat is very important. I didn't have one but luckily there is a shop that also rents out all equipment you would need for trekking or hiking. I rented a rain coat for 6 pesos.
Clothing/Shoes/Weather Gear: The weather can change very rapidly in the mountains so you should wear layers, starting with the Tshirt as it can get quite warm and finishing with a warm jacket. I was taking it off one by one on the way up and then slowly putting it on again on the way back:)
Good foot wear is essential. The terrain can get marshy and it is important to try to keep your feet dry. There is a lot of good walking to do here.
Toiletries and Medical Supplies: No Medical supplies here besides band-aides and alcohol.
Photo Equipment: The small shop in the center of town is very limited in film and related equipment. It is also very expensive. There is a Kodak store in El Calafate, so make sure you stock up because this place is gorgeous. Be aware that the Kodak shop in El Calafate is closed on Sundays.
Camping/Beach/Outdoor Gear: El Chalten has limited to no outdoor gear. In fact it is better to bring this stuff from home and not try to acquire it in Argentina.
Make sure you bring your sun glasses as the UV rays are quite high here in this part of the world. This is essential with a snowy ground reflecting the light right back up at you.
Miscellaneous: There is a small shop in El Chalten that sell various products but there is little in the way food here especially produce. Stock up in the excellent supermarket in El Calafate before coming out here.