Your topology is mostly very good, but I think that your shading problem is that the area I marked with the crude blue box is a 5-pole.
I would use the knife tool to add the edge I crudely drew in orange, and then I would select the two diagonals leading to the pole and dissolve them.
You could fix a similar problem with the next diagonals down, if the ...
Add a text,
convert it to curve,
remove the "double vertices" so that you got one single line per letter (i did it just for the c, because i was lazy) like you see in C:
uncheck cyclic in your curve object
add a circle as curve
give this circle as bevel object of your text curve
you might to adjust the circle size and character spacings
Your problem happens in step 6. If you rotated the Bezier Circle when it was in Object mode, then applying the rotation causes the orientation of the bevel to change on the Bezier Curve. Also, you'll get right/left confusion if you rotate incorrectly.
You can fix the former by not applying the rotation. If you try to move the right side vertex on the ...
I guess it depends on how detailed you want your object to be, if you want to make close-up shots you'll need to take care of this part, if it's not the case you don't need to work this part a lot. You can also fake the bump. But if you want to model it, you can create an edge loop:
Then extrude a bit on Y, then a bit on Z:
Then add bevels to round the ...
You're bevelling the edges of the face and increasing the bevel so much that it's overlapping. The actual geometry of your object is fine. Looking at your first image, it looks as if you just want to bevel the corners on the ends in which case you should go into edge select mode (2 on the keyboard - 1 in the image below) and select the two end edges of your ...
The Remove Doubles command was replaced with Merge by Distance, but it's still in the same location. In Edit mode, go up to the Mesh menu, then Cleanup, and finally Merge By Distance. You will get the contextual popup down in the left corner where you can adjust how close the vertices should be before they are merged.
If that's what you are asking, that is.
It is because of your topology. You have a big ngon face on top and bottom.
One way (the brute force method) to solve this is you could add a remesh modifier, set to sharp, octree depth something bigger than 6 (maybe 8) and then render again.