CMU Arch in Existing Wall and CMU infill

[msdmoney]

I have a couple questions on a project I am working on, looking to get some feedback on a some options.

1) I am designing a new opening that is being cut in an existing wall. The door is approximately 12' wide by 14'-6" tall, the 14'-6" being the top of arch with a 3' rise. Looking at options of using a steel header/lintel or CMU lintel. I've seen plenty of resources for achieving this with brick, but I'm trying to find some resources for achieving this with CMU.

a) Is the typical manner with a cast in place lintel to use narrow u-shaped lintel blocks for the arch portion, and then chamfer the edge blocks that at the jamb for the compression? There is plenty of wall on either side for the thrust.​

b)I'm assuming the typical shoring option for this (although only shown schematically on the design drawings) would be needle beams above the new lintel, since the temp channels option straight across is out because of the arch.​

c)I'm also sizing a steel jamb behind the wall for the out of plane loads​

2) Also in another area, they want to infill an existing roll up door. that is framed by CMU. I'm concerned about using a large infill wall here that will change the stiffness of the wall, but wondering if I'm being overly conservative since I'm already removing stiffness in another wall with the opening (but analyzing it for the new loads imposed).