Replacing Three Elbows and Pipe

[VermonterBC]

I am in the process of finishing our basement where our woodstove is located. The stove heats the upper two floors of the home as there are large metal grates above the stove that allow the heat to move upward. The stove vents into a brick chimney through a stainless liner (non-insulated). The stove is a Pacific Energy Super LE. For some reason the stove pipe from the stove has three 90 degree elbows to get to the brick chimney. When we finish the basement, I’d like to go straight up from the stove and use one elbow to go right into the chimney. I’d also like to remove the large metal funnel-like contraption to channel heat into the grate above. A few questions…

-The 6” pipe that goes into the chimney is the male (crimped) end of the pipe. Is this acceptable? All I read says crimped end should be facing down.
-Does this section get attached with three screws? As you can see in the photo, the masonry material used at the entrance to the chimney doesn’t allow for much room for screws.
-I’m unclear if a thimble exists here. Or if it’s needed given it’s a brick chimney.
-Can/shoukd I use double wall pipe off the stove and transition to the single wall at the chimney? Is there an adapter for this transition? Is the needed clearance to the ceiling 18”? Doing this should move the stove a few inches closer to the chimney as we will remove two of the elbows.
-Any other considerations to take into account?

Thank you!