I assume English is not your first language so I will try and make a stab at answering your questions based on my interpretation.
You can adjust the pump timing without access to VCDS. But how will you know if it's correct and not too advanced or retarded? If you don't have access to VCDS then take it to someone who does, take it to a dealer, or just leave it alone.
does thes leak effect the power to much ?
If the pipe is leaking you are not getting the required amount of boost so yes this will affect power drastically.
ps perhaps if you added the details of where you live there may be someone who speaks your native tongue and could assist you better. Save you struggling with English.