#1 make an oil cooler yourself, theres a DIY here somewhere;)
#2 get SOLID mounts… will be loud and “rickity” but your gona get used to it and you will never experiance a blown mount which will make you think everything is broken but the mount…
#3 Dont rebuild the Rear subframe… find a used JDM rustless subframe, pay to powdercoat it and replace your stock one(might aswell do a 2way dif when your at it)
and for parts… go to intense… if youve never installed a clutch have them do it for you… not something you wanna play around with, may cost you your motor and tranny.