If I disconnect my battery due being away for 4 months

Should be good to go. Just make sure the battery is charged!

Disconnect battery for an hour ,it may have gone into safe mode make sure all the fuses are in right places and none blown.

Most likely the piktail or also known as the alternator connector no good.

Only problem I can foresee is if you vehicle has the antitheft system that you have to put a code in for the radio. Also. you injectors would lose their prime. So before you tried cranking the car, turn the key to the run position and leave it there a few seconds, and repeat that twice to reprime the fuel system. other that that, there should be no problems. Hope this help.

Pull the connections on the battery and leave it disconnected for 10 minutes. Reconnect and test.

see if throttle body need to be cleaned

It sounds like you have an aftermarket alarm system, if it's not factory. First check your key rings, did the vehicle come with a remote entry/alarm? If it did and just stopped working, check the battery and replace it. If there is no remote, there may be a small toggle like switch under the driver's side dash pannel, someware lower tord the petals. if not, try leaving the key in the ignition in the "on" position with the door open before you try reconnecting the battery. Try that, and if that doesn't work still, disconnect the wires (black and red usualy) to the alarm horn, where all the noise is coming from. Good luck!

try to disconnect the contacts and clean them, put some grease on it, them reconnect the cables.
try to check also for the ignition relay, it might be loose, reconnect them if possible

sound like your brake switch or the fuse.
you have to step on the brake to take it out of park and if it doesnt see that the brake is being pressed it wont unlock the shifter
later paul