Better stick to own design instead of hire someone design for u. It will be costly and result might not meet your requirements.

Interior designers mostly copy design from magazines. During design also many house owners are the one that tell what they want and the designer just put the ideas together

No, my house just basically the same. The renovation is just back extension and relocate the main door. 

The TV designated location was on the West wall. So, the main sofa would be close to opposite wall (East) and the door was on the right (North). Once you open the door, you are exposed to outside world    That's the main reason.

Sometimes it is hard to imagine before hand what you want to add and which is better and practical. The contractor of my previous house was good. During wiring stage, they asked me if I wanted to add more power socket or switch. The for has house drawing sketch so I could mark the point. The charge is much cheaper that adding point after the house was completed.

For my current house, I laid big 60A power cable before the extension work took place so that I have another separate DB box at the kitchen. Serve as distribution point for air-con power point for other rooms at the back and also for the kitchen. The house developer only provided the power point for master bedroom. I did the wiring with my friend and costed my 1k+. I think the contractor would have cost me about 6k 

No. The house was bought before development. It was just that during each construction stage the developer sent letter to ask if you want to add power point and additional wiring. Most developers won't do this. When installing the sliding door and windows, they asked if I wanted a dark tinted glass (not film tinted). I declined, but when I got the house the glass was tinted. Get it for free 

nowadays renovation costs so much.. save up the ID money to do more nice things for ur house. just need to go thru more show units and magazines to get the ideas

I last renovated my condo was 5 years back,  I did not engage any ID services, just my bro in law introduce this contractor to me, in the end the contractor said what most forummer suggested, which is buy some ID mags and get some ideas or walk around furniture fair get some idea take pictures and show the contractor then he will draft a 3D floor plan with all furniture inside. TBH, the end result is so so only, after putting all furniture eg sofas coffee table dining table etc into the house I feel my condo abit weird, cause do not have the designer feel or atas feel despite spending so much. Everything is like so rojak.

If you have the budget and if you want your house to look good I'd suggest you to hire ID, casue they will design everything accordingly and even go shop furniture with you which matches your theme. That is if you have extra budget, nowadays ID easily cost 6-10k

go google app download 'houzz' can make reference to whatever designs you like. they even have links to the designers if you want (in uk tho). if you no budget just copy paste and compile yourself. im doing the same