I'm sorry you had such a rough trip. I'm usually a pretty staunch defender of Continental, however some of their Newark customer service agents...well, let's just say, it's Newark after all. I spent more than half my life in the New York metro area and service such as you received in Newark is somewhat par for the course. I know "please", "thank you", and "I'm sorry" go a long way when dealing with travel weary customers but you just aren't going to get that from any airline employee at any New York airport including Newark and Continental. It isn't right but it is what it is. If you're familiar with the TV show "Seinfeld" and the "Soup Nazi" character just imagine a whole bunch of "Soup Nazis" only they're airline employees. The "Soup Nazi" was character was based on a real person who owned an actual soup store in New York City!
Now as far as the other part of your complaint, weather was most definitely an issue at Newark on Sunday, August 2nd. If there are any doubts
just check some of the posts on FlyerTalk.com about Continental's Newark operations that day. Looks like the weather started to get bad about 10:30 in the morning and was marginal throughout the day. Inbound flights were diverted all over the place and outbound flights weren't taking off. It was indeed a mess and I'm sure the employees and passengers alike were stressed to the max.
I'm not sure why the agent even mentioned the bomb scare at LaGuardia because it occurred the day before, August 1st, and would not have impacted your flight from Newark. Even if it had been the reason for your delay the temporary closure/evacuation of an airport for a suspected security breach comes under those things which are not within the airlines' control and therefore you wouldn't have been compensated for a hotel room anyway. In your case the delay and subsequent cancellation of your flight was clearly weather related and unfortunately the airline will not pay for a hotel under those circumstances nor will they rebook you on another airline.
As for your change in destination again the airline, unfortunately, isn't obligated to compensate you for time or expenses incurred to drive to your original destination. You see when they offer an alternative and you accept it you are agreeing to a change in the contract between you and the airline. Instead of being contractually obligated to fly you to your original destination they are, after you accept the new modified terms (change of destination), not obligated to carry you any further or compensate you for your expense to get there. I realize the option of waiting another day or two in Newark to fly to St. Louis wasn't a pleasant one but when given your choices you chose Kansas City. Had you opted to remain in Newark you could have gone to the airport to stand-by for the sold out flights and very often after a weather disruption people decide not to travel and there are no-shows. Of course sand-by isn't a guarantee and waiting around at the airport with elderly family members isn't a real option either.
If you'd like to pursue a complaint about the general lack of customer service and the attitude of the Newark employees I can provide you with an e-mail address of someone at Continental who will respond to your complaint. Unfortunately you can't expect compensation for any of the other things you list, especially "discrimination of the elderly." About all you can expect is an apology and perhaps a voucher to use on a future Continental flight. If that possibility seems agreeable to you please send me a private message and I will provide you with the e-mail address.