I'm no expert, but I spent several long weeks last summer machining a lot of 304. It can be a real pain, as you have read, but there are a few things that may help...
A lot of bars that are sold as 304 are actually 304L. I believe that this variation of 304 includes additional Lead which reduces the extent to which it work hardens (much like 1214 Steel versus 12L14). It's still not 'free machining' but it's a lot better. Infact, I don't mind turning 304L.
In addition to work hardening like crazy, 304 has a lot of carbides included in the metallic structure, meaning that it is very abrasive. I have worn through TiN-coated carbide cutters very quickly because of the abrasive nature. Addressing both of these problems requires aggressive cuts that remove the previously work-hardened area on each successive cut. I used very beefy negative-rake tooling to rough the parts to size, and finished with a normal brazed-carbide tool (which I had to constantly re-sharpen). As a side note: I was using a Clausing Colchester 15 lathe with a CXA toolpost. The BXA toolpost on a smaller lathe couldn't withstand the forces caused by the negative-rake tooling.
Unfortunately, I cannot address the 3"-ID boring operation. I had to repeatedly perform a similar operation... each of which killed one corner of a triangle-insert boring bar. I did not use coolant as it was not available for that machine. Perhaps a coolant bath would extend the tool life.
Correction: Thanks to Peter Neill, the L refers to a "low-carbon content." My mistake, but thus why I prefaced it with "I believe..."