Thanks for the correction
Sorry for the bad name writing

(had problem when trying to tag you as it have tagged someone else

)
For -j4 some people say that's okay other says what you said
I'll put in tips and tricks the command to know which number of job the CPU is able to use it will be better i think
For chmod +x build.sh I don't have problem of permission but i can add it if people encounter this problem
For zimage-dtb I'll update the post too as it can apply to arm too
Thanks again for these correction