Just a note on flashing. I have an electronic timer that can be set in tenths of a second. (If flashing is the route you want to go) what I have done is to make a guide at the usual magnification levels I generally print at and the paper + a contrast (Aristo VCL or use a filter) in tenths of a second fully processed and dry. I can see what the flashing (no negative in the carrier) will be. I can then know how long I want to flash for. Of course sometimes you have to make an adjustment for the final print but you could preflash at different times on a test print sheet. Couple this with some of the suggestion above.

http://www.jeffreyglasser.com/