Unplottable Hogwarts? Plottable Durmstang? Or vice versa?

[tub_of_earwax]

No: HPFGUIDX 41723

In PoA Sirius traveles to Hogwarts. How does he do that if Hogwarts 
is unplottable, and has all these charms on it? the only possibility 
I could think of was the following: 
He first traveles to london, goes to platform 9 3/4 and follows the 
train tracks of the hogwarts express, to hogwarts. For this Hogwarts, 
to my thoughts, would not even have to be unplottable, if you can 
find it by following the train tracks, what's the use of making it 
unplottable? Then again, maybe the train doesn't have any tracks. We 
could assume it to be a magical train, right? 

Where does it state that Hogwarts is unplottable? It says that 
Durmstang, and I think also Beauxbatons is, but Hogwarts? Does it 
actually say, or does Hermione only give it as a possibility as to 
how to keep a magical school secret? 

About Durmstang. I've spent a great part of yesterday on my encarta 
cd-rom. I took the map of Europe and tried to find some countries who 
could be candidates for the location of this school. I do not htink 
it is situated in Bulgaria, because the temperature in Bulgaria, is 
not low enough for Krum to be going for a swim in the lake, when it's 
freezing in scotland. Which is the problem with most of Europe, the 
temperatures are fairly mild, not reaching much less than an average 
of minus 5, in normal winter. About the same as Scotland. 
Because this is what we know of Durmstang :
1) It is located somewhere cold, because of their uniform.
2) It is located in Europe, probably eastern, if you look ate the 
accents, of the students of durmstang. 
3) It is located in a country which has a lot of water (lakes, seas 
or oceans mostly), or which has to do with a lot of water. Because of 
the Dumstang ship, why else would you bring a ship?

I've come up with the following countries. 
1) Romania. This country would be pretty perfect, because half of 
it's border (the south one) is with Bulgaria for one (so close to 
Viktor's home country). The eastern border is with the Black sea. 
Romania has a couple of lakes also. Third of all, there are parts of 
Romania that have really cold temperatures. It can get up to -34 
degrees C in winter, in some places. Romania is also probably THE 
magical, or at least creature wise place in Europe. Vampires, 
Werewolves, Dragons etc. If JKR has set Durmstang in Romania, we 
would be able to visit it easily, since it's also the place charlie 
stays, with the dragons. 
2) The scandinavian Countries. Mostly probable of those is Finland. 
Since Finland is almost all water, to my knowledge. And colder than 
Norwegia. Finland, along with the other scandinavian countries are up 
north, so the temperatures are a bit colder than the rest of Europe, 
but not as cold as the all time low in Romania. These countries have 
viking history, who were excelant sea farers, and always had the best 
ships. With language, even though I have not that much knowledge of 
scandinavian languages, it doesn't seem to completely fit. So 
basically only sea wise it fits more than Romania, for the rest, 
Romania gets the points. 
3) Another country that's VERY cold, and has borders with the ocean 
and of course lakes, is Russia. With language it could match. But 
somehow my gut doesn't say Russia's it, you know? It could also fit, 
since Bulgaria had ties with Russia because it was a communistic 
country, but that was only since after WWII (I know muggle history, 
but if often parralels wizard one, or has influence on, like 
Grindlewald for example). Durmstang is MUCH older, so communism 
doesn't really coun as an argument I would say. 

So What do you think? Hogwarts unplottable, did JKR make a mistake 
with sirius just walking onto the grounds, and where is Durmstang?
Have fun. 

Lara