This is gonna take quite a bit.
Feat 1: Usage of the formula is alright, but the source for Antarctica's Diameter might be referring to the measurement of the furthest tip to the other. That being said, my concerns are largely unfounded so I guess there's not much I can say to dismiss it.
Feat 2: Honestly, agree with what KLOL said about it being fine mathematically, but the way the timeframe was extracted is rather dubious.
Feat 3: This one seems fine judging based on other calculations utilizing this formula.
Feat 4: Now I am going to have to sit myself down for this one. Now the OP of the blog does state that he is using a formula he found on StackExchange, which is essentially a question-and-answer site for active researchers, academics, and students studying physics. Now to be perfectly honest, I have studied and researched what in the world this formula is supposed to be. After a lot of thought and deliberation, I find that the formula is built on so many aspects with torque, magnitude of angular momentum, angular change, and so on. Essentially, the goal of all of these variables is to find the Work done by Torque, but honestly, due to the Work-Kinetic energy Theorem which is pretty much W = K_f - K_i, I feel as though what is done in the blog is rather tedious when honestly applying Rotational Kinetic Energy in this situation. Which I will go on ahead to do.
KE_rotational = 0.5×I×w^2
w is the angular velocity
I is the moment of inertia around the axis of rotation
The angular velocity is based on how quickly the amount of degrees the object moves in rotation. Since the angular change is 66.5° and assuming the force of the explosion caused the Earth to shift in a second, we get an angular velocity of 1.1606 rad/s.
I = 8.04×10³⁷ kg·m²
Therefore, KE_rotational = 0.5×8.04×10³⁷×1.1606^2
That would come about to 5.4149092872e+37 J or about ~12.941 Ninatons of TNT (Large Planet level+)
Feat 5: Now for this one, there are a few things I can comment on. First is the discrepancy of the fingers. Yeah, surprising to see that now, huh? What I specifically mean is about the hand pictured in the comic panel. If the hand in the panel is using the left hand, then the finger would be the left index finger which is the number the OP of the blog is using. But that would contradict the intentions of the blog poster telling us that they're using the ring finger. If the hand in the panel uses the right hand, the right ring finger length should be used. Granted, this whole line of analysis only shifts the results minorly, but if the OP goes out of their way to identify the values they intend to use, they shouldn't be ignorant of what they're using.
Also, agree with KLOL's statement about this feat, too. Now I do have one actual point of contention about the way they used to find the AP, but I will make that its own post if asked to.
Feat 6: I remember long ago that the arm span was about 0.8× that of your full height, but I can't seem to corroborate with anything I still have, so honestly this is fine.
(Ik this is essentially a necro of the thread, but watching this be dead in the water kinda rubs me the wrong way. ̶A̶l̶s̶o̶ ̶w̶h̶o̶ ̶i̶s̶ ̶D̶D̶M̶?̶)