Go ahead and drive it daily, that's what these cars were made for. If you live in an area that you are worried about theft though, then definitely look into getting a security system, because classic cars are VERY easy to steal.
As far as safety goes, well you've got a padded dash and lap belts, that's about it. I think they also switched to a collapsible steering column in '67 to, so you don't have to worry about it impailing you in a head on collision. If you're concerned about safety then you can get some 3-point seatbelts, that will help a lot in a collision, considering that a lap belt will only keep you from flying through the windshield while allowing you to hit your chest or head on the steering wheel or dash.
These are really fun cars to drive, I love drive my '65 Mustang everyday and I wouldn't trade it for anything. These cars were meant to be driven so have fun and be safe, you'll love it.
Of course you can all you need to do is make sure you take care of it with proper tune ups, oil changes and keep the tires and brakes in good shape. I drove a 1964 Galaxie daily from 1973 to 2002 and that is no kidding, the only reason I don't drive it now is because I got a new car in 2002. I do recomend an alarm system just to make sure it stay in your hands.
Just remember the brakes are not like today's cars, leave more distance between you and the car in front of you.
If you're concerned about stealing, when someone wants your car you can't stop them. But you do want to keep the causal thief away. If you have an automatic, put a translock shift knob on it. You can also put a hidden cutoff switch that keeps voltage from going to the coil too.
Why not! I have a 1963 2 door Nova. I do have to say it needs an exhaust repair at the moment. However...when it gets fixed it will be driven daily. Yeah people may want to steal it, but my husband installed a kill-switch in it, it would take a lot to take my car. That and I have a view from my desk at work! LOL! Drive that 1967 Mustang!! You are only young once!!!
Sure, you just drive according to the cars and your ability. I wouldn't worry to much about it getting stolen, unless you have a lot of expensive gear on it or it's a rare model like a Shelby or fastback..