Hi, and welcome to VK. This group includes some real Admiral junkies-- er, experts, so I'll let them answer the hard questions.
Re Question #4, the slanty retrace lines, they are common to many 1940s TVs that lack vertical blanking circuitry. If you're not interested in modifying your set, the remedy is turn down the contrast until they just disappear.
I haven't tackled any Admirals yet, although I have a similar model waiting in the garage until its turn comes up. You can see a photo in this
thread. Maybe this winter . . . .
Phil Nelson