Framing question, basement/first floor remodel

enoll

Hello -- First time posting here, and would appreciate any feedback or input from you all. Thanks in advance!
I am looking for some feedback or input on my framing plan for replacing a door and window. Some background... We are working on remodeling the first floor/basement of our 2000 sq.ft. house (about 1000 sq. ft. per floor). Doing all the work ourselves. There is a door and set of windows that we are going to replace. We want to replace the window for more efficient ones (this is the original, single pane aluminum window), and importantly, to make the room feel taller. The existing door is short, the RO being 75 3/4" high. We would like to replace it with a full height door (6'8"), and also raise the adjacent windows, which have an RO of 4' h x 8' w to the same height as the door. This will make the room fell much more like a typical height. In addition to replacing the door with a 6'8" one, we are going to replace the 4' h x 8' w window with a set of three windows. The dimensions of those will be, 2' w x 4'6" h, 3' w x 4'6" h, and 2' w x 4'6" h. This will leave room for framing members between the windows.
On to adjusting the framing for the bigger door and windows...
There is currently a double 2"x10" header over the door, and a double 2"x10" header over the window. This is the bottom floor of a two story house, and a load bearing wall. Existing door, window, and framing:

In order to open the openings higher, I need to use a much smaller header. So over the door, I would like to remove the existing header and replace it by removing a section of the lower plate of the double top plate and inserting a either a 3 1/2" x 4 1/2" parallam or two 1 3/4" x 4 1/2 LVL s that would span the 34 3/4" RO. The reason we decided to replace the one big window with three smaller ones was so that we could use a smaller header. So over the windows, I would like to replace the existing header with the same material and dimensions as the new door header (either a 3 1/2" x 4 1/2" parallam or two 1 3/4" x 4 1/2 LVL s) that would span the 8' wide RO. However in between the windows would be mullions, or double trimmers supporting the header. Again, the windows are 2', 3', and 2' wide. Proposed plan:

I think this should be fine, the largest span being just over 3', and the extra strength of engineered lumber should carry the load more than adequately. I would rather not interrupt the double top plate, but it is only the lower one, and would use steel straps to reconnect the plate. So...

1. does this seem a good plan for adjusting the framing?
2. which is better to use for the header, parallam or LVL?
3. what is best for a steel strap to reconnect the interrupted double top plate (just the lower plate will be cut to accommodate the header)?

Thanks!