Try to help here a bit where I can.
First, as said, forget the jumper cables and wire it right. Good connection from your batteries to the inverter with heavy wires. You could get by with heavy duty jumpers perhaps from the car to the extra batteries, but not jumpers to the inverter!
Side mount battery in your car would be very bad! You should have a top post battery for connections. You can buy cable ends for top post type batteriers that have a bolt sticking up also, getting a set of those and bolting the conection would be best but more trouble and you should disconnect when ever your not running the engine so you don't end up with a dead car battery.
Better than using the car at all, find a junk lawn mower that runs, use the engine from that to run a GM 1 wire altenator for charging your batteries. Use alot less gas and it works better and is portable so you can put it places the car won't fit 
Do a search here for homemade 12V gennies and you should find some posts about these.
Very easy to build if you can tinker a bit.
A good small windmill would be good to start to. Once you have everything for emergency use you can use it full time and save on your power bill also, not just wait for the next storm. Search here about some of the DC motor gennies. The 200Watt wood one is nice, not really alot of power, but why not go for some extra power full time cheap.
You probably have ALOT of golf courses in your area, T-105s are used for golf carts, look for used ones and save a bundle! Either from golf courses or cart service and sales shops. I can get them here for $10 each
Golf carts use alot of power and no-one wants stuck on the 17th hole with dead batteries so they are normally replaced even though they are fine.
T-105's are actually 225 amp hours when figured at the normal 20 hour rate, not 110amps. Most deepcycle batteries are figured at the 20 hour rate. In RE service we don't normally put the high load on a few batteries like driving a golf cart around half the day. Heck I even had the golf cart dealer tell me T105's are 110amphr batteries, then someone here told me they were 225amp hour, then I checked right on the trojan battery website and they say 225amphrs at 20 hours.
T-105 is a 6V battery, you have to use them in pairs wired for 12V and 225amp hour per pair. Use several pairs, many as you can buy. Getting back to the amp hour rating at 20 hrs, the more batteries you have the less power each battery has to provide under any givin load, less they have to provide the longer they will last. Your total AMPs available from a battery will encrease the slower you discharge it. So at say 20 Hrs you get total 225amps, but at 6 hours you may only get the 110amps. So if the load is constant (basically) then spreading it out over a greater number of batteries will let them discharge slower, extend the run time, and also provide more total amps. That is compared to trying to run the same large load on say 1/2 as many batteries which drains them faster and they then provide less total amps. So more is better here in several ways.
What Steak said here,
"12V @ 110 AMPS = (1320 watts) ie; 110 Amps/hr = is 1 hour with 1 batt.! 3 batts gives you about 3 hours till they are drained 100%, given ya really don't want to discharge past say 50%, that knocks it down to 1.5 hours of cool air...!!"
That is correct and draining them that fast is hard on them so you'll probably kill them before long. Also as I said, faster you drain them less total amps you get so in 3 hours you may not even get the 330amp/2= 50% @ 165amps total from 3 sets. Course if you have power from a gennie/car at the time you run the airconditionare that helps a great deal, you'll be using the 60-100amps from the car and the batteries making up the difference somewhat. It is hard on a car engine to idle long periods like that though, and at an idle you'll probably be getting less than full power from the altenator depending on your vehicle and other variables.
You may want to reconsider the airconditionare for now or use it as little as posible. At 110Amps (actually more) at 12Vdc you will have to run a car putting out 100amps for over an hour for each hour of air you run just to catch up, even if running the car same time as the air you loose over 10amps from the batteries per hour, even if all were perfect which it won't be. But at least you can have fans and other goodies anyway that use less power.
