Because "hus" is an ett-word. Jag is describing a person so it counts as an en-word. Depending on that you use either värt (for ett-words) and värd (en-words).
Mods may correct me if I'm wrong.
No, många pengar is only said as a joke in Swedish. (Or sometimes when speaking about coins).
Probably like how in english, you wouldn't say "The house is worth many money" That just doesn't really make sense.
Yes, the reason is that pengar and money are uncountable, and for those we use mycket and much respectively, många is only for countable nouns.
Why "the house worths" is wrong? The house is worth doesnt sound right to me...
Sorry, Poliana, but we can't say "the house worths". "The house is worth..." is just how we say it in English. :)