OH YES bendikr5, with your code problem 2) is solved.
BTW i’m thinking that using physics wasn’t a good idea for the kind of game i’m trying to develope 
have to try with non physics collisions.
Problem 1) is still unresolved, help is really appreciated.
Have you testet your game on a device? The lines should be less there.
Some solutions to the flickering lines can be found here: https://forums.coronalabs.com/topic/54068-tips-for-drawing-tilesets/
@AAAle I just saw this idea on another forum that you might want to try to get rid of the lines.
display.setDefault( “isImageSheetSampledInsideFrame”, true )
This will likely fix most of your tile gap problems. Set it before you load any tile images and / or make sprite sheets from tiles (and don’t forget to reset it afterwards).
Here are the Corona docs on this attribute: https://docs.coronalabs.com/api/library/display/setDefault.html
“isImageSheetSampledInsideFrame” — Affects how image sheet frames are sampled. If set to true, sampling is intruded by half of the source texture pixel size to avoid border artifacts. Default is false.
I found this info on this forum: https://forums.coronalabs.com/topic/61724-how-to-create-a-platformer/?p=322280
Kudos go to rakoonic.
Wow, just testet it and that seems to work! Thanks for sharing!
You guys are awesome!! everything solved! Thanks for you support