I want to get the LCD 512 GB Steam Deck, but I have some worries about it

  1. can I put in a 256 GB micro GB card or SD card into it and not worry about storage anymore? Will the loading times drastically increase because the game is on an SD card?
  2. Can I stream my pc games onto the Steam Deck? There are some games I play that aren’t available on steam, or on the deck in general, but I still want to continue playing them.
  3. Will I be limited to only steam games, or can I play other games as well? If so, can you list some places I can get games on the deck?
  4. Is there any better alternative to the steam deck that is under $500 that i should buy instead?