Lt_Duckweed

This is actually the issue.

Deeper in the atmosphere = higher atmospheric density
Eve = higher pressure, CO2, both mean higher atmospheric density
Eve = higher gravity, meaning you need more lift to fly, so for a given speed you must fly in denser air than on Kerbin
 
Eve has 70% more gravity than Kerbin, so you need 70% more lift, which means, with the same plane, roughly 70% more drag.
This means 70% more thrust, which means 70% more torque needed.  If the torque needed is higher than the rotors can supply, the rpm starts to bog own.
The inconsistencies of KSP building can mean that the two rotors have different torque to thrust ratios, so one bogs down slightly earlier

Exposed surface area of a part's drag cube causes drag.  Node attachment has a side effect of reducing this exposed area.  Thus reducing drag.
See my earlier post in the thread.  It's not about the node being occupied/unoccupied, it is about the relative sizes of the parts that are atached at the nodes (NOT node size, it is based on the actual visual cross section of the part)

Not quite.  Ksp calculates drag based on exposed part surface area.  There are a couple ways to reduce the exposed surface area.
1. Place the part in a service bay, cargo bay, or fairing.
2. Node attach parts.  When you node attach 2 parts, the two node atached faces have the area of the attached face subtracted from their exposed surface area. Thus, the smaller face has its area set to 0, and the larger face has the area of the smaller face subtracted from it.
There is an additional "streamlining" factor applied to each face of a part (each part has 6 faces) at play, the "pointier" and more aerodynamic a face is, the lower the factor is.  (The front face of a nosecone has a low streamlining factor. The sides, being less pointy, have a high factor).  Infinite streamlining has a factor of 0, a perfectly flat plate has a factor of 1.
Rapiers have a very flat back end, with a factor that is nearly 1.  Adding a nosecone removes some of the exposed area on the rapier and replaces it with the much more streamlined area of a nosecone.

25-30 tons is a good starting number, and as you get more skilled at building sstos you can push that higher.
To understand how to build sstos around these numbers, watch this video, it is the best ssto tutorial out there: 
 
If I'm making a "sporty" ssto where I don't care that much about squeezing out every last drop of performance I use about 35-38 tons per rapier.
If I'm going for maximum possible performance I will take off from the KSC flats and use anywhere from 44-52 tons per rapier, depending on the exact mission parameters.

A large drill has a base rate on asteroids of 5 ore a sec, which means it can power 10 recipes.  A small drill has a base rate of 1 ore per sec, so it can power 2 recipes.
To get more fine grained:
The base rate for the liquid fuel + ox mix is 0.5 ore a sec for .55 ox and .45 liquid fuel.
The base rate for ox only is .55 ore a sec for 1.1 ox.
The base rate for liquid fuel only is .45 ore a second for 0.9 liquid fuel.
The base rate for monopropellant is 0.5 ore a sec for 1 monopropellant.