Boardwalk is one of the good guys, no need to stick it to them.
That's interesting about the $1000, give them a call and ask them about it (no need to ID yourself as a tenant).
In a fixed term, the tenant is responsible for the entire term of lease, though the landlord has to make every effort to re-rent it and if they do then you are off the hook.
It sounds to me like with this $1000 thing they're making it simpler, instead of making the tenant responsible for everything just making a simple way to get out. I would guess the $1000 is instead of being on the hook for rent until May.
Either way you should not lose your security deposit.
Look at it this way, if you get your place 1 month early, then you have a month to move rather than a day
Plus keep in mind that your mortgage payments typically don't start until 1 month after the deal closes, so you won't be paying for both at the same time.
If not, give your notice now and they're obligated to start advertising it, and they'll likely have someone ready for when you move out. Or as others have said find someone for them (though they have the right to qualify them).