As it is written: “And they camped by the Jordan from Beth-Jeshimoth to Abel-shittim” (Numbers 33:49), and Rabba bar bar Ḥana said: I saw that site and it was three parasangs in length.
According to Wikipedia, one Talmudic parasang is equivalent to 2.41 - 2.85 miles. So three parasangs are in the region of 7.2 - 8.6 miles.
Q1: Your first question is a good one. I can suggest a couple of possible answers:
אין מוקדם ומאוחר בתורה - It's possible that the story of Menashe's conquest of Gilad happened prior to the two tribes talking to Moshe.
This is another piece of evidence that Bnei Yisrael always intended to capture the Gilad - and didn't just happen to capture it because ...
As @Dov and @N.T. wrote in the comments, a couple of centuries isn't a long enough time to be considered having a lasting name, and there is indeed evidence that the name didn't last: In Divrei Hayamim 1:2:23 it says:
"But Geshur and Aram took from them Havvoth-jair, Kenath and its dependencies, sixty towns. All these were the sons of Machir, the ...
Sometimes a picture is clearer than a thousand words. Does this illustration (taken from the Stone Chumash) help build the right mental model for what the Torah describes?
Or, in the words of R Steinsaltz's commentary
An area extending 2000 cubits in each direction was alloted to each
city (see Ramban, Ha'amek Davar). One thousand cubits of this
To answer your second question, I don't think it's a typo. I think it depends on whether you count Ramesses. It's considered a stop in the overall 42, but they didn't actually travel there. That's where they left Egypt from.
On your first question, the first 11 encampments being in the first year is based on the verses that say that Bnei Yisrael were still ...
Those who were regarded as able to actively serve in the public domain were being counted. Those over sixty were in effect retired from the army. Thus when the punishment of the 40 years was decreed, those who would have served in the army (20 to 60) at that time were being punished. Those below the age of 20 would not have been eligible to be drafted.
According to the Mizrachi, Rashi's source is a beraisa in Sifri that points out that verse 8 there says:
All the days of his separation he is holy to the Lord.
Since that verse refers to the Nazirites personal holiness, the reference to holiness in verse 5 seems redundant, so the Sifri applies it to his hair, based on context. In other words, the Nazir ...