Usually brakes will lock up if there is brake fluid on the pads. I find it hard, but not impossible, to believe that this is the case...but you never know. The hard brake pedal would be caused by not having sufficient vacuum to make the booster function. Fix you vacuum problem...not much worse than needing to stop on a dime and hitting several thousand $$'s instead. This ought to take care of the doorlock problem too. With some luck it is only the large rubber diaphragm that needs replacing. You can do this in an hour (including washing your hands after). When you do the repair look and remember where everything goes.
hope this helps
-Larry

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