need to calculate the difficulity of the coin, the hash rate and the electricity cost. u gonna open it 24/7. do refer some setup online, they using amd rx 580 x 6gpu. and its profitable. not sure if other setup would have a good ROI as those.

One GPU only, im not sure whether it can do the job. u might get a low coins mine

What is the withdrawal time for Luno to Maybank as compared to other bank? From the withdrawal schedule, once it reaches withdrawal release time, does it mean that you will see it reflected in your bank?

Unfortunately, in Malaysia, we really do not have much choices.
It's not that the site themselves price the coins too high, it's that generally the liquidity in Malaysia is too low to sufficiently even out the buy/sell spread to match global average prices.
Meaning, there are a lot more people trying to buy cryptocurrencies, compared to the amount of people selling.
This imbalance in demand naturally causes the price in Malaysia to rise higher than global average prices.
Personally, I tend to see prices in Malaysia usually around 2 - 5% higher than on US exchanges.
That's still not too bad, considering the fact that in some countries, the premium can go up as high as 10% or more.