Architechture/ Foundation help for a drupal project I am thinking to develop my drupal website for various products like camera, mobile and others.

For this i will have various content types like camera and mobile and others and have term references for feature of products so that it will be helpful in filtering the products.

Now my big problem is here. 
1. Each product i.e camera, mobile should have its rating properties like camera will have its own set of rating properties and mobile will have its own rating properties. How do i attach these rating properties to a content type ?
2. When user goes to the product page, He should give ratings for properties and add comment against each property. How ill i do this ?
3. If he has already given ratings and commented on the product it should be default displayed.

Main problem is that how do i attach rating properties to the content type and make user comment on these properties.

If i create separate content types will it be a problem to create a search on all products
I'm not sure what you mean by "properties" in your question.  However, you can use the Fivestar module to add ratings to a content type. So your Camera content type could have a rating for each camera and your mobile content type could have a rating for each mobile.

Search will work across all content types. http://drupal.org/documentation/modules/search