Cards on the table vs in your hand

[patlhunter]

I purchased Munchkins Deluxe this week and have read the instructions -- some sections multiple times. However I am struggling with what cards can be placed on the table ... both normal and sideways as well as what cards to keep in your hand.

Some items are obvious like armor but others not so obvious.

Are curses something you can place on the table sideways?

Other than "additional" big items, classes and races are there any cards you can not place on the table sideways?

Can you use a sideways card (one-shot/curse) during combat? Or should that card always be non-sideways anyway?

I am sure I am over complicating the whole thing but wish it was a little more clear in the instructions.

Thank you in advance.