#1 - I can't reproduce this. I've given a Sprite object with a private variable of 'Number' type an initial value of "Hello". It works fine, all that happens is the runtime interprets the text as a number, which does not crash - usually it just gives the variable a starting value of 0. You should send or upload a .cap that crashes so I can take a look, since it doesn't sound like initial values are a problem...
#2 - I'll take a look soon, could you add it to the bug tracker?