Working black pipe

Can someone tell me if working with 3" black pipe is allot harder than 2" black pipe. Is there a big cost difference? What tools are needed to be able to thread black pipe? I know I need schedule 40.

The reason I'm asking is because Garabedian plumbing used 2" pipe for my riser and header in spite of the fact that my boiler manual says to use 2-1/2" minimum. I pointed this out to them and they won't fix it so it looks like I have to either fix it myself or find a contractor to do it which leads me to another question. How much should it cost to have a contractor re-pipe the riser and header with 3" pipe (see picture)? I want 3" pipe to get the exit velocity of the steam way down so I get good dry steam. I did a quick calculation and 3" pipe puts the exit velocity down to 13 ft sec, 2-1/2" is about 18 ft sec and 2" is over 25 ft sec.

The boiler (Weil McLain EG 40) has a 3" tapping. I have 276 sq ft of radiation and the boiler has a net rating of 325 sq ft. The water level in the gauge glass surges all the way up the glass when it's steaming toward the riser and I'm afraid that if the water level tilts too much the last section in the back will be overly exposed to the flame and crack. The water level tilts while the boiler is steaming because the steam exiting that 2” riser is exiting too quickly and causing the water level to tilt toward it. I also have spotty uneven heat compared to before but no hammering or spitting vents.
Thanks