My family consisting of 2 adults and 3 kids will be spending one week holiday in Netherlands, Brussels and Germany before departing to Edinburg. Below is my itinerary.
July 1 ( Monday) - Amsterdam
July 2 - Amsterdam
July 3 - Bruges ( visit Antwerp on the way)
July 4 - Brussels
July 5 - Cochlem
July 6. - Cochlem
July 7. - ?( not sure)
July 8 ( Monday ) - ? ( not sure)
Below are my questions:

1)We would like to fly to Edinburg either on the July 7 or 8 and not sure which airport and cheap airlines to take.
2) We will be traveling by train and it is better to buy normal tickets or by Benelux - Germany Railpass.
Please comment and give suggests to my itinerary.

Thank you
Chew1

First off you are moving around too much to allow you time to see and absorb anything of the locations you wish to visit.
1 That depends on your final destination on the week(or is it 8 days) in the the countries you wish to visit.
But like I said you are travelling around far too much.
2) To see if rail passes are for your advantage read through the following website.
http://www.seat61.com/Europe-train-t...m#.UVLaFFdc7oY

Dear ribeirasacra ,
Thank you for your prompt advise. We are Asians and really not familiar with the whole Europe train systems. I planned this based on the reviews from the forums and see only what are necessary and try to cover as much as possible.
I planned to go to Edinburg on the 8 July and really can't decide which airport to fly to Edinburg. Like you said, I am moving around too much, may be I should only visit Netherlands and Belgium , forget about Cochlem .

Thank you

You haven't factored in any jet-lag time, or travel time.
I would add at least another day to Amsterdam, maybe more if you are dropping Cochem. If you drop Cochem add time to Amsterdam so you can see more of The Netherlands than just the city.
Antwerp could have a day, Bruges a day or two Brussels a day.
You could then fly to Edinburgh from Brussels. www.brusselsairlines.com have cheap flight to Edinburgh.

Dear hetismij2,
Thanks for the recommendation. I arrived Amsterdam early in the morning 6.30 am , so I have 2 full days in Amsterdam. We are quite a fast moving type of travelers and jet-lag can be easily overcome by just moving around.
I will look into Brussels airlines flight to Edinburg.