If you run extension cords, remember that the longer the distance the heavier the wire gauge needs to be. I have a 25 foot extension for the 30 amp outlet on my camper and it is 10 gauge. Smaller wire gauge cords can be inefficient, heat up and even start fires with a heavy current load. This goes for both 110 AC and 12 DC. Also, you should never plug a generator of any type directly into a household 110 volt/15 amp outlet. Appliances should be connected directly to the generator through an adequate cord. I'm sure you know this. but never run a car, generator or any type of "charcoal grill" in a garage or enclosed space. Please remember that connecting a generator improperly to a household fuse box (through an outlet) can: 1 burn out your generator through an overload or worse, burn it out when the power comes back on, 2 kill a lineman working on restoring power down the line by "backfeeding" current and transforming it to lethal levels.
If you set up a "whole house" generator system, you should have an electrician install a "transfer switch" that will isolate your system from the utility lines when you are using emergency generation. If you go this route, you either need a generator big enough ($$$$) to supply all the appliances that will be running at once, or you need an auxiliary breaker box to "zone" the power to only one or two circuits at a time (my home is set up this way and I can get by with a much smaller generator).
For the short term and less expense, get the minimum items you need for safety and some comfort that will run on 12 volts, either a deep cycle battery or regular "flashlight' batteries. All of my critical, short term items run on lithium "flashlight" batteries. lithiums have a long shelf life, 10 years, and will work better in cold situations, and last longer than alkalines. Don't even bother with regular carbon "Heavy Duty" batteries. I don't trust rechargeable batteries in critical emergency items that may sit, unused for a length of time. LED lights are available everywhere and are the most efficient. I also have some of those "solar garden" lights. In an outage, put them in bathrooms, hallways, stairs as low level "marker" lights. I keep them on a window ledge so they are charged constantly. Camping outfitters also have many types of brighter, solar lights that can fill a room. Of course, lighting is only a concern at night or in enclosed rooms. A bigger concern is running a refrigerator (keep it closed and it will keep food safe for 24 to 48 hours, depending) or pumping well water (if you don't have city) and that doesn't work well on a small battery set up.
One last thing. They make battery adapters (kind of like nesting Russian dolls) that will let you insert a AA cell into a "C" cell adapter, that can then be inserted into a "D" cell adapter. I stock up on lithium AA cell and these adapters will let me use them in any battery operated device (lithiums aren't made in "C" or "D" cells).
