I am doubting whether the surrounding things are tahir or not because I have a background of urinating while sleeping,

1) Can I consider them pure if they don’t have stain of urine and doesn’t stink.

2) Suppose a surface is najis (for example cloth or metal) but is dry so when I touch it with my dry hands do my hands become impure too?

3) Does that mean Najasat can never be transmitted if both the things are dry i.e hands(najis) and clothes (Tahir) or Clothes(najis) and Hands(Tahir) etc

4) Does sweeping on a surface that does not absorb water make it clean i.e. a marbled floor but it has joints and you are uncertain if water can sweep in it

1- If you are not certain that it is najis, you can consider it pure.
2- No.
3- Yes
4- If you mean pouring water on such surface, then yes, it becomes pure.