Best place to tell what/when reissues are released

This is not specifically the answer that you are looking for, but it still may help. I recently moved to Arizona, and in the Phoenix region, there are a large number of Goodwilltores (seven or 8 within reasonable distance of my house) where used records are always available for 2-3 dollars. Every other Saturday, everything is 50% off. I have bought great records, including what some would consider desireable (original copy of Harry Belafonte at Carnegie Hall) in great shape, as well as a lot of other great titles. You should really check it out if there are Goodwill stores near to you.
It is also a great source for used CDs. I have bought many in great condition...some never even unwrapped! Same prices.

Take a look at soundstagedirect.com They seem to be right on top of most of the Rock type reissues that seem to be coming hot and heavy,right and left,week after week.There are some discount mail order houses that offer vinyl as well,Deepdiscount.com and Blowitoutta here.com.The latter two have spotty stock and never order anything on backorder as it will be thrust into the black hole of cyberspace only to appear months later.Also,make sure you have a decent return policy for any vinyl purchased,and as we get into the summer time Media mail is a less advisable option as things go slow and can simmer in hot trucks or even rail cars that move the mail at less than priority shipping rate.
Goodwill is always a fun option for patient and adventuresome vinyl pursuits.

SS Direct is very good. They always identify original pressings vs. reissues. But they are expensive.

One suggestion is to subscribe to elusivedisc.com, acousticsounds.com, and musicdirect.com newsletters.