Disclaimer: I'm an absolute beginner in my Finnish studies, and if the answer to these questions are obvious, I humbly cry your pardon.

At the moment I'm learning basic things like counting, simple nouns, and ( relevant to this thread ), days of the week. In practicing them, I couldn't help noticing two things;
1) Words for a few of the days seem suspiciously similar to those of Germanic languages. First and foremost, Torstai. Is it a coincidence that it seems a lot like "Thor's Day", AKA Thursday? Then we have Sunnuntai followed by Maanantai....Hmmmm.. Am I to believe these are etymologically unrelated to Sunday and Monday

2) Keskiviikko, while admittedly not sounding anything like Wednesday, has the obvious distinction of being the only Finnish day of the week not ending in "tai". I'm sure there must be a good reason for this, and I'm very much looking forward to finding out why. Is this a mark of honor for dear old Hump Day, a branding of shame, or something more arcane?

Thanks in advance for humoring me and my curious/ignorant self!