Customise my Imei unlock site by adding feature from my other site and e-commerce to sell physical products

If possible I want to add e-commerce section to my unlock site that will have payment gateway and connect or PayPal, PayPal express, stripe, square, and visa/master card payment method via api maybe? Also to have shipping integrated with auto calculate cost on buyer address need to connect at least to auspost and dhl via api maybe easiest way?

Also want to customise current theme so it includes products from new e-commerce add on to landing page and add invoice script and inventory and repair script like ones I have on my other site to Imei unlock site so everything I need is in the one admin panel product.inventory and spare parts inventory to mimic one like I have. With pictures and barcode label make and print

Repair terminal to have portal on site for repair customer to log in and use likescript I’m using

Also change currency on site

Current site

GoldCoastUnlocks.com.au
(Purchased thru Imeisoft)
Want it to look more like this

User Panel
* http://www.demo.pro.nakshsoft.com/
* Username: demo
* Password: demo

Repair portal inventory invoice at

Goldcoastcrackeddevices(.)com.au
Here demo
Login

admin@admin(.)com

P@33W04d

From this I want copy few feature to main site