install new HU pioneer AVH-1300NEX - newbie questions

[eden]

im not an american so my english is not so well but i've tried to write this post as clear as i can.

i've mirage 2014 (made in Thailand) with some unbranded Chinese junk system (see attachment).
i own this car for 2 years and i cant live with the current HU so i've decided to buy this one PIONEER AVH-1300NEX

before i will buy a new dash panel i want to try to install it on the current dash panel (i dont care if there will be a gap).

the most important thing to me is the steering wheel control. i've read many threads here in this forum to learn as much as i can about my car.

if i understand correct the easy way is to buy some adapter(?) for that purpose? or if i want to save some bucks i can do it myself?

which Wiring Harness I need to buy?

Beside that there is anything that i should know before installing myself the new HU?