Replacing Load bearing wall in basement
Ambitious project with lots of issues: 1) loads on walls, 2) temporary supports, 3) size of new bearing wall, 4) connections, 5) soil conditions, 6) size of footing,

1) I’d verify that the roof does not sit on the wall. If it does, it makes things more complicated, but not impossible. Is this a single story house? Is it located in (a.) high wind area, (b.) seismic area, or (c.) high snow load area,???

2) I like your plan of having two temporary walls...is this due to joists lapping on the bearing wall? Keeping each temporary wall about 3’ from the bearing wall is reasonable. Remember, the transfer of load into the soil is at a 45 degree angle. That is to say, the transfer of loads from the temporary wall should not impact the soil (and edges of you 18” wide trench) 3’ away. (We’ll talk about the width of your footing later.)

3) If the new bearing wall will only be 8’ or 9’ high, then 2x4 studs at 16” oc are acceptable. Will it sit on the subfloor or is that balloon framed also? 

4) How the new bearing wall is framed will determine how it’s connected to the footing and ceiling (above). 

5) The type of soil will determine the size of the footing, required reinforcing (rebar), likelihood of sluffing, etc. 

6) I like the continuous footing idea, but it may need to be wider. (Going from a timber width to 18” seems reasonable, but if we knew more about the type of soil and total load, we could determine if it’s wide enough to support all the loads. 

So, to answer your question, no, I don’t see any major problem, but if you could answer the above questions, we could help more. 

Btw, a few pictures of the attic, etc. would help.