When exiting Thailand, your current visa or visa exemption will be canceled. Be sure to do so before the 60 day stamp expires. When entering next time, you will show the DTV and get a 180 day stamp.
The stamp is not the visa. A visa is an allowance to enter the country. The stamp says when you have to leave.
No, it's likely going to be denied. Unfortunately they're very very strict when it comes to dates and names matching 100 % with the passport information. The site really tells you to double check the data before submitting.
I understand that you are nervous but the embassy people are not likely to work weekends and their load is probably quite high now as it's high season. You don't state what embassy you applied to (and this isn't a DTV question if you applied for SETV) so unable to guide you further, but your embassy's home page might have info on it about their processing times. And although it's an e-visa, its a manual process.