Custom Form / Installation of 1.1.8 / Customize Payment

[heyseoul]

Is it possible to link the "Check-out" button on my customized Form?
Or is it possible to edit the Check - Out Form?

I already download the zip file of the 1.1.8 , how can I install it on my AbanteCart Cart?

Can I customize / add my own Payment Options?

[eCommerce Core]

Please do not put many questions in one post if you want to get straight answers. 

There are many posts and documentation that covers installation and upgrade.
http://www.abantecart.com/ecommerce-documentation/20-installation

Yes, you can add your own payments.