Good morning dorlov and welcome on forum.
I think you emailed me today about this same issue so i will try to answer it on here too.
1. if it is 3d mini sublimation machine (this is the one i own) then yes. you do pre heat mould, but before you put plastic case on.
2. this video may give you start;
https://www.youtube.com/watch?v=JtnWci7 ... AH_nnVSr5Q
3. Is always good to use as best picture as you can get. Industry standard for printing is 300dpi. iPhone wallpapers are small images suitable for screen if you need print it you will need higher quality image.
4. You already have one from me so you should be alright with it

ICC profile has nothing to do with blurring.
Get your time and temps correct and i am sure other issues will go away.
all the best
Paul