Anyway, with regards to the research penalty:
If you want a tech that was historically researched in say, 1940, and you start researching it before then, you will get a penalty. How large the penalty is depends on how far from the historical year you are, and this is calculated in days. So in the above example it makes a difference whether you start the march 27, 1939 or october 15, 1939. The penalty will get smaller for every day that goes by, so your research speed will go faster and faster, untill eventually the penalty dissappers on january 1, 1940 (assuming you didn't finish the research before then). There's a limit to how large the penalty can get, and I think it's about 2-3 years before the historical date, however imo it's never worth it to start researching anything that early, no matter how much you need it (often the penalty is so great that you would probably finish around the same time if you started later). A rule of thumb is to not research anything earlier than a year before the historical date.
Btw, there's no bonus for researching later than the historical date, so I usually research all of the techs that have no penalty (that I want), before starting to research ahead of time, unless there's something I really, really want.
Edit: Here is a link to a research faq.
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