Effective lighting layout is affected by a lots of factors such as how bright the ambience you prefer for each areas, entertainment, sleeping and working areas can have different brightness.

Other factors like ceiling height, wall color scheme, ceiling design, whether there are any concealed light cove will also affect the lighting set up.

So I can just give you a rough ideas for referencing only.

I think you should get the 10W eyeball, as 5W normally are use in cabinet lighting. I also find out these eyeball you choose have a narrow light beam angles of 24 degrees, you will need more numbers to light up a full wall

Try to get a broader beam angles like 36 or 60 degrees may be, that can bright up the area better.

If you are using a wider beam you can generally space the downlights 1.2 to 1.5 metres. If you are using a concentrated beam light, try spacing them 1 metre away from each other.

I will suggest you having some 12 - 18W LED downlight at the middle of living and dining area. As normally people use eyeball to hightlight the wall, painting and decorations. LED downlights will be more effective and generate a more smooth ambience and even brightness to the space.

here is the lighting layout I suggest for you, hope it give you some alternative ideas!

As long as you position the LED downlights more than1800mm apart from each other and avoid the downlights being obstructed by the ceiling fan should be fine.

Speaking from my experience, go thru the ID's project in ATAP again, n find a few design u like.... narrow down to 3~5 ID and ask for proposal (normally they will present u the mood board, the direction they gonna design ur house).

yes, u nid to tell them wat u like, n ID will satisfy house owner but the design sense n idea of designer will b different for every ID. So, it is really depending on the ID to design sth tat match ur taste and budget. Each ID hav their own signature design style.... n if u engage an ID tat is nt good in doing the style u like, tat will b a nightmare....

Just my 2 cents.... 

Yea tats wad im afraid of. Actually shouldnt be the ID n the contractor both come over at the same time to discuss? So anything doesnt make sense or difficulty can be discuss on the spot.

Is now a bad time to proceed with any house reno work if I haven't started anything?
I've been getting news about understaffed design firms (not enough designers and project managers), insufficient labour at contractor side as they rely alot on foreign workers and last but not least the ever increasing material cost. In addition to that, most firms are still catching up on their mco backlogs I believe?