Pastrami is indeed healthier than bacon because pastrami does contain less fat than bacon does and also less grease than bacon.
Still pastrami is pretty high in salt and sodium which can make the pastrami unhealthy in excess and can lead to heart disease, high blood pressure etc.
But in moderation the pastrami would be healthier for you than bacon.
Pastrami is also lower in calories than bacon so it's better to eat Pastrami when you're losing weight or need to manage your weight.
But even eating too much Pastrami could cause weight gain.
Pastrami meat is a processed food.
Processed food does include Pastrami as well as other foods such as beef jerky, corned beef, hot dogs, ham etc.
Any meat that goes through a curing process or a smoking process, is salted or any meat that goes through a process that alters it's taste or to preserve it or enhance the flavor of the food is processed food.
So yes Pastrami meat is a processed a food and in excess it could be bad for your health due to the high salt content.
Pastrami is good for up to 5 days in the refrigerator.
You can safely leave Pastrami meat out at room temperature for up to 2 hours and if it's been past 2 hours since you've left the Pastrami out then it's best to throw it out because of the bacteria that grows on the Pastrami meat at a fast rate when left out at room temperature.
If you're not gonna serve or eat the Pastrami within 2 hours then be sure to refrigerate it to keep bacteria from growing on the meat.
If you want to keep Pastrami longer than 5 days you can and should freeze it and when frozen the frozen Pastrami meat will last for a year or more.
However it's best to eat the Pastrami within 6 months for the best taste and quality.