Wikipedia is darn handy, and provides a wealth of information. It won't tell you what the entry interface altitude is for a particular planet, at least not in a way that is directly usable in Orbiter. It will, at best, give you a "starting point" for further investigation.
In Real Life nothing is launched into space without rigorous testing in a computer simulation. Why should things be different in Orbiter?
It's not that hard to test things in Orbiter. Just pretend that you are doing "pre-flight simulations".
Try to use scientific principles in your tests - make them repeatable, and try to have a "control" to compare them against. For example, when I designed my ascent and re-entry profiles for the DGIV i followed the following steps.
1; Design a test procedure that gives usable information. I decided that what I needed to know was:
A; the minimum velocity required to maintain level flight at any given altitude,
B; the maximum velocity I could attain at a given altitude without overheating,
C; the velocity where, at a given altitude, drag forces (in m/s) became more than gravitational forces (also in m/s)
2; Establish a "control". To establish a "heat" control, I flew a DGIV straight up, and cut the thrust when I vessel had an ApA at the altitude I was testing (I decided to test for every 5k altitude). This resulted in a "stall", an instant where my vertical and horizontal velocities were very close to zero - and I noted the external and hull temps (note that I kept the velocity under 100 m/s during the climb to help prevent the hull temps from reading too high as a result of friction during the climb) at that point.
3; Data Gathering. First, for every 5k altitude, I did test flights to determine what the minimum velocity was that would allow me to maintain altitude using the wings, using only elevator trim to maintain attitude. Next, I accelerated at that altitude until the hull temps hit the red. I recorded every flight so I could watch the replay and get data without being distracted by having to fly the vessel. I watched the recording in external view with "visual helpers" enabled so I could see the actual thrust, lift, gravity, and drag forces.
In the end, the data I gathered led to some conclusions. One was that it doesn't pay to break the sound barrier until you are over 10k altitude. Another was that a DGIV will NOT burn up (at normal re-entry velocities of under 8km/s) until you are under 64k altitude (at least in Orbiter 2006P1, and some preliminary testing shows this seems to be the same in 2010P1).
In short, some flights I "pretend" are done in a simulator to gather data, and some flights I "pretend" are For Real. After all, that's how real spaceflight is done - they just don't have to "pretend".
I'm not a math wiz, so I tend to use methods that are a bit on the crude side. The important thing is to use the scientific process - Gather Data, Make Hypothesis, Test Hypothesis. Tests should be designed to be repeatable (make each test several times, and if you get notably different result each time it means your testing method is flawed), and to exclude the "interference" of conditions not being tested for (ie, control the environment as much as possible).
I don't know of any chart that gives you this info, as it applies to Orbiter. You'll have to test it for yourself (and maybe you could be the one who creates the chart)!