welcome dude,
For all maintenance DIY, it aint that hard, theres guides on here that can help if you get stuck, same for mods, bolts ons are usually just that, bolt on easily.
If you do want to go to a mechanic for your car, look in the "where to get Skyline serviced" thread at the top of the ACT section.
As for insurance, shop around and good luck.
plant the right boot and enjoy!