Can anyone recommend any good shops around Cheras that do good waxing and polishing? thanks.

How about polish only when necessary? If u think your paint is in good condition, then why polish? Coating doesnt mean u can stop caring for your car. If u read the quote from Par@dox, coating has even more need for care.

Personally my 2 sen, since u say your paint is in good condition, then maybe at best u can get some off-the-shelf spray wax or sealant and just spray and buff after every wash. U can probably then maintain it beyond the next 3 years and more.

Then I'd say a coating is not recommended in your situation. Imagine this, you are driving back home and it rains and your car gets wet with some dirt / traffic film on it.

If you don't wipe the car dry when you get back, the rain will eventually dry on your car and water spots will develop on the coating, which unlike on wax / sealant, are much more difficult to remove. Also, if you wipe your car without washing it first, very likely you will scratch / mar the coating, so you will need to wash it first before wiping dry. Alternatively, you can use rinseless wash but it's a hassle as well.

By cleaning sunroof u mean removing the water spots from the glass on the sunroof?

Have been using this and quite effective yet reasonably priced available from Ace Hardware outlets

Can give a try on the Soft 99 Iron Terminator basically its just removing the iron particle which makes the wheel cleaning easier .

Aside you may also try Carpro WheelX or even Koch Chemie MWC were also excellent choice.