A small, lightweight, and portable butane or propane gas canister would be most suitable for use on a backpacking trip. These canisters are easy to carry and provide a reliable source of fuel for cooking while on the go.
Assuming you mean on the walk itself, yes provided it is self-sealing or screwed to the stove, and without leaks.
For outdoor cooking, you should use a camping stove canister that is compatible with your stove model and fuel type. Common options include propane, butane, and isobutane canisters. Choose a canister that is easy to transport, refillable, and provides the appropriate amount of heat for your cooking needs.
No, it is not safe to leave a butane canister in the stove.
A fall in air temperature can reduce the pressure inside the butane canister, leading to a drop in fuel flow rate and flame intensity on the camping stove. This may cause the flame to be smaller, flicker, or even extinguish if the temperature drop is significant. It's important to regulate the stove to maintain a consistent flame in colder temperatures.
This would depend on what you are planning on doing at Yosemite. If you will be staying in one place for the visit, then you should bring all the necessary camping items. This would include: Tent, stove, water, food, sleeping gear, first aid kit, bug spray, etc. If you plan on backpacking through the park then I would recommend packing much lighter or buying equipment made for backpacking. You will still need the essential items, but remember that you need to carry everything you bring with you for the whole trip. http://www.ultralightcampstore.com
You can purchase a camping stove at any major discount retailer like Target or WalMart, as well as at any camping/sporting good store. Stores that specialize in outdoor sports and wilderness camping can also help you choose the stove that best for you.
Lightweight stoves or cooking fores are a great option to use when camping or hiking. The lightweight stove is light enough to carry to the desired camping spot, whereas a regular stove is not.
Coleman has a good run of the mill camping stove, but if you are looking for something lightweight and portable this may not be for you. The SnowPeak Lite Max is a stove I can recommend from experience. While it is nothing fancy it is definitely portable and is priced reasonably.
Trangia stoves are small stoves intended for backpacking. They don't take up much room, for ease of carrying. All versions of this stove work with gas burners.
You would boil the contaminated water in the camping stove with the handkerchief above it, ensuring it doesn't droop into the water itself, then wringing it into the cup to gather water.
To safely use a propane tank stove while camping, make sure to set up the stove on a stable surface away from flammable materials. Check for any gas leaks before lighting the stove. Always supervise the stove while it is in use and never leave it unattended. After use, allow the stove to cool down before storing it properly.
Good foods for camping are foods that will not spoil on your trip (if you are camping with a cooler, this includes pretty much anything you eat at home) and foods that are easy to cook at your campsite. If you plan to cook over a fire or a simple backpacking style stove the best foods are foods that can be cooked on a grill, on a stick or in a packet of foil like hot dogs and other meat, marshmallows, baking potatoes, corn and foods that can be boiled like noodles, soups, corn, and veggies. Canned foods that just need to be heated up are good for people who are uncomfortable with cooking in a primitive kitchen. Other good camping foods are foods that don't need to be cooked at all like sandwiches, crackers, chips, and fruit. That said, you really can eat whatever you want when you go camping: the deliciousness of your camping food is restricted only by your own creativity and ability to cook in a primitive kitchen. For a backpacking trip the best foods are non-perishable foods that are lightweight, high in nutrients/calories and use a minimal amount of fuel to prepare. Foods like nuts, dried fruits, beef jerky, powdered soups, pasta, couscous, parboiled rice, and dried veggies. There is advice and good recipes for backpacking at the website in related links. The website is about hiking the Wonderland trail around Mt. Rainier but the meal planning advice works for any backpacking trip.