1.) Check your alternator. If you have a multimeter handy, use it to check the voltage of the battery with the car off. If the battery is good, you'll get about 12V. Start the car and check again. With the alternator charging the battery you should see about 14.5V. If that's a lot lower, chances are your alternator may be crapping out. There's also a chance that there's a bad wire that's not allowing the alternator to charge the battery properly. Autozone can do a diagnostic test, as well as a few other places; you might want to go that route.
2.) There are a lot of possibilities here. Most common are plugs (and plug-related things like wires and coil pack) and fuel pump. Fuel pump will usually show problems when the tank is at 1/4 or less. If you fill up does the jerking stop? As far a plugs, they may be worn. The plug wires may be brittle and cracking; if you run the car in the dark you might see sparks from the engine. At 73k its possible the plugs and/or wires are failing from normal wear and tear. I had a stumbling problem at 80mph that was due to using non double-platinum plugs. I switched to OEM Autolites and the problems went away.
