Technically speaking, although both are cryptocurrencies, ETH does not compete or contend with BTC as they were developed to serve different purposes entirely.
Purely in terms of price, though, nobody will be able to predict how either one will be priced in future. One thing is for sure, both are here to stay.
But with BTC having a market capitalisation of 20 times more than ETH, if ETH wants to overtake BTC, there is still quite some ground for it to cover.
Nope, both XBit Asia and Luno are online exchanges......you only deal with the exchange, you never meet the buyer.
You just log in, transfer your bitcoins to the exchange account, set up your sell limit, and that's it.
Once someone agrees to your price and buys your bitcoins, then the exchange will execute your sell order automatically and fund your account with MYR, which you can then withdraw to your local bank account.
It's very convenient. Just like your normal stock exchange.

Hang on......let me go get my crystal ball......aaaaaannnddd......my crystal ball says it doesn't know either......
If I could predict the future like that, I wouldn't be sitting in front of my computer typing on forums......I'd be sucking rum out of coconuts on some exotic beach in the Bahamas instead. 
Having said that, I do not think it is outrageous for ETH to overtake BTC at some point in future, just that it would take some effort and time.
Having ETH hit USD 100 by the end of the year is not really that hard, though.
We're only in March, and ETH is already nearing USD 16.
As cryptocurrencies become more mature and mainstream, there will be much more capital inflow to the industry, and demand will always drive up the prices in the long term.