yea mate any loose rust etc will need taking off first or the paint wont stick to it. If ur doing alot of metal and have access to a compressor and dont mind spraying it urself buy a tin of etch primer rather than a can and spray all the bare metal surfaces with 1-2 coats, then your best bet again is some 2k primer again spray out of a gun if u can. You can obviously use cans instead but for the amount of bare metal it looks like u have in the pics you'd go thru shit loads