A standard “rule of thumb” is 1/3 to 1/2 of the boiler volume for the thumper. This will give adequate “headroom” in the thumper to avoid puking from the thumper into your product condenser.
Shotgun condensers are usually the most efficient, meaning they use less water to sink heat into. But shotguns are more difficult to build. They also can be shorter overall length because of the bank of vapor tubes versus a single vapor tube common to the Liebig.
Other condenser designs, Liebig and Graham condensers for example, have advantages and disadvantages, often construction difficulty being the deciding factor when choosing to build.
A flake stand is effective when coupled to a potstill and/or a thumper and represents the “classic design”. But, they are not as efficient because of the volume of water needed to condense the vapor. The worm can be critical to build to ensure the coil always has a “downward” spiral to avoid pooling of condensate within the worm.
Electric heat is probably less expensive energy than propane or wood fire. It is also easier to manage control of the heat input (which can be useful for controlling the vapor production rate). However, the first cost, or cost to acquire the control system will be higher than propane or other direct-fire solutions. Often, distillers prefer one over the other because they already have the equipment from other utility. But out of demand, electric solutions are more available and cost effective now compared to the past.
Electric powered boilers are often cleaner and quieter to operate than a noisy, smelly “jet burner”.
If your requirements include a “remote location”, then portability may dictate propane power over electric.
In conclusion, all of your questions are subjects of much discussion and varied opinions within the website’s forums. The fact that you ask the questions you have in the manner you have indicates that you have not yet spent enough time reading the many threads throughout the website. So, your eyes have not yet begun to bleed even though you feel they have. You’re just getting started.
ss