Rick, the longer radius fittings the better for uniform flow. I would also consider a clean out prior to any change of direction greater than a 45 Degree angle.
About connecting 3-4″ lines I would seriously consider increasing the pipe these three connect to a minimum of 6″ to make sure you can handle the volume if each pipe should be discharge near capacity. My personal choice would be a 6×4 long turn double sanitary tee or a combination of a double wye and 1/8 th bend with a clean out on the run. This would allow for a smooth flow plus easy rodding just in case.
As it is connecting 3- 4″ dia pipes to one 6 inch line is still slightly under sized but it should work BUT check your local code.