for target local market better domain  with .my or com.my
hosting dosent matter as long not too slow.

Any usual  Linux webhosting provider should have no problem with OpenCart, Prestashop or any other php e-commerce platform. Being e-commerce platform, all have built-in shopping cart. You just need to add payment processor/gateway to receive payment from customer

Do some reading on payment gateway of the platform you choose, commonly payment processor like Paypal/Payza is the easiest and you don't need to pay anything to use it but if you want to be able to receive local bank transfer from your customer you need payment gateway like ipay/molpay etc

But are you sure you want to handle the setup and the business/management side yourself? E-commerce platform is a b*tch(to setup and maintain) and I would highly recommend using hosted solution like Shopify or Prestabox for people who just want to sell their product.

Any particular budget?
Just an advice, make sure you ask your prospective host first whether e-commerce platform that you choose will work well with their particular plan. I've heard that Magento are slow/unresponsive on shared hosting

if you are looking for .net
Exabytes will be offering it at only RM3.99 on 31-Jan-2013 for first 100 signup on that day.

even if you are not looking for .net domain, you can consider to buy additional .net domain to park them together at your hosting so that you get more than 1 domain pointing to your website.

it depends whether your hosting package allow you to host only single domain name or multiple domain name within a single shared hosting package.

Some hosting package allow only 1 domain per hosting account
Some hosting package allow multiple domain but all of them park on a single website (park domain) per hosting account
Some hosting package allow multiple domain with different website (addon domain) per hosting account but all of them sharing the same hosting control panel login
Some hosting package allow multiple domain with different website per hosting account where each of the domain have their own control panel

you may wish to check with your hosting provider to make sure on what is allowed in the hosting package you subscribe to.