Yes they can
No, A Number or chaos form cannot be destroyed by god cards expect by another number card, spells, or Trap cards.
The best ways to prevent your cards from being destroyed are with monster effects or Counter Traps. Stardust Dragon, Solemn Judgment (now limited though), Dark Bribe, and even Destruction Jammer can all save your cards from being destroyed. There are few, if any cards that specifically prevent your continuous spell cards from being destroyed, although Field Barrier saves your Field Spell cards from destruction.
Houses Likely Destroyed
If you are talking about grave yard ...... you can. But on the show the cards are basicly destroyed.
YES by their effect or by the card "Pyramid Of Light"
then all cards on the field are destroyed unless the union monster has an effect that says that it can be destroyed instead of the equipped monster
There are 20 such cards.
If you mean, is it destroyed when it 'levels up', then no. It is simply 'sent to the graveyard', it is not a 'destroy' effect and cards that look for or trigger from something being destroyed, will not activate.
Not counting the face cards nor Aces which do not have a number, there are 16 odd numbered cards.
In Uno, the number of cards dealt out to each player at the beginning of the game is 7.
To get Power Cards, you will need a coin number or a book number.
48