When steeping grains, all you are doing is disolving and rinsing the sugars off the grains. It's not like mashing where you have to get the enzymes to convert the starches to sugar first.
Steep around 165 F. No set time, but you need to get the grains up to the water temperature to disolve the sugars. Stir as much as you can to keep rinsing the sugars off the grains. The longer you leave it, the more sugars you will get, but I suspect you will have gotten most out of it within 15 minutes.
If you are using a grain bag, you can get a lot more of the sugars if you have a second pot of with a quart of water at 170 F that you rinse the grains in after taking them out of the main pot. 1 quart of water is enough for up to 1 lb of grain.
You can use paint straining bags for grain bags, you will find them in the paint section of hardware stores. The 1 gallon bags are good enough for 1 lbs of grain, and the 5 gallon are good enough for 5 lbs. If you use a bag, do not have it in contact with the bottom of the pan while you have the heat on high, or it can melt.
Try and get the grains out by 170 F. Tannins can start leaching out above this temperature, but don't be too concerned if you do overshoot, it's not going to be too much. Just make sure you don't boil the grains.
Some people practice late extract addition (myself included), but I would recommend for your first batch you follow the kit instructions.
It's a personal thing, but I believe the LME should be added before the end of the boil. It needs to boil to create the break material that precipitates out. Even with late extract addition, I add it before any of the late hop additions as it stops the boil for a short while.