He sure did perk up when the puppet entered the scene.

It is something that just takes practice.  You can practice without the puppet on your hand and try moving just the thumb. I can sometimes help train your brain to move just the thumb if you can see it. I've never worked with one of the Whatnots before but I have had to deal with puppets that are a bit tighter in the jaw then others. Over time they tend to loosen up a bit.  The fatigue is something you'll also get used to with practice.

Welcome to Puppets and Stuff.  You have some ambitious ideas.  It is kind of hard to give you direction without knowing what your skills are.

I well say that you might need to scale back a bit on your first idea. Even professional puppeteers don't normally try to make a single puppet do all things. Often more then one puppet is made to accomplish different things. BTW even though you are inside it is still considered a puppet. Mascot or body puppet would be the term most would use. There are body puppets that do the things you want but often they have a second puppeteer that is operating things via remote control. Vacuform plastic can be light weight but often is not really that durable. You might be better off going with traditional fabric over foam construction. I well say that 2 hours in a body costume is not feasible. I've performed body puppets and my limit in a costume is about 30 mins before I need to take a rest.

My suggestion for the shoulder puppet is for your friend to buy one.   I am pretty sure they have seen one of the many that are available out there.  They are your idea 3 and controlled using your control option 3. You need a universal ball joint in the neck of the puppet that translates down to the ball/knob at the hand.   

Never used Reddit. You are welcome to post a link if you want.

I feel you have to take the puppets personality into consideration when you are designing and building. A villain is going to have different features then a hero. Where would the Grouch be without his scruffy fur and heavy brow?  A good visual for this is to do a Google image search for Cartoon Villains then compare to Cartoon Heroes. 

If they have quirks or mannerisms it is very possible that you need to construct the underlying structure a bit different. While with a hand in mouth puppet this may not be as critical can be very important with other styles of puppetry like marionettes or rod puppets. The joints may need a bit of tweaking to attain certain mannerisms.

I can kind of understand what you are talking about. I well say though that the more puppets you create the more this feeling well most likely wane.

You need more then one suspension point.  Think triangle, three point.  That should give you more control.  Would need to see the shape you are working with to give you better details.

I would go with the PVC set up. Takes up less floor space.  Also you could turn it around to the back and hang your green screen off of it when working.   You can easily weight the bottom just like the stanchions by filling with either sand, cement or plaster of Paris.

Great post Brian! Thanks.

Welcome back! Nothing exciting to report on my end.