Few Questions about Extra mode

[Handlebars Fakis]

is there some form of patch for this to get more missions / weapons / units?
how do i get said patch?

[JCGamer]

^^ there is no patches for PSU anymore not for offline. there is however Modding patches and hack mod weapon and for the offline story with Cheat Engine
here are these 3 Video Guide by Game Time on how to do thing. All link and patch mods is in his video Info. and be sure to have a 4share account before getting his mods patches

you can find it here on the video link
https://www.youtube.com/watch?v=lBbcirFWF5A

and swapping weapon and armor u can find here
https://www.youtube.com/watch?v=N7QOJF9nZFI

how to make all tech skill at lv 50 you can find it here
https://www.youtube.com/watch?v=G0siU_1wx1g
and this hard part to remember . You have to understand how Cheat engine work in general

remember this only work with PSU AOTI JP Version. So don't be a noob just follow his Guide and you wont have any problem and also be aware Modding and swapping is a lot work to understand C.E and you will gonna find buggy problem and be aware of that aswell and make a Full backup of all your file when dealing with Modding and Hacking for the offline story mode ;-)
and to get cheat engine you have to Google it.