Jvalread

I've had my car for almost 7 years now, bought it brand new. I haven't had many problems with it, however within the last two weeks is started freaking out when we try to turn it on. Previously, only needed to press clutch and turn key, now at the very least we have to give it gas at the same time, but it also with cause the doors to lock, the horn to honk, the dash lights flicker. And that's if it starts at all. Sometimes it will just click like the battery is dead.
also how difficult is it to fix the door lock, the drivers side lock fell into the door about 5 years ago. It has a key fob which locks and unlocks the door without needing to use the lock.
thanks