Designing Kitchens and Bathrooms - help with kitchen desk

I am installing a desk in my kitchen. It consists of a desk cabinet, knee drawer and countertop. It will be attached on one side to an existing cabinet with the cabinet on the opposite end and knee drawer between. I have MANY questions and would appreciate any help!

1. After installing the desk cabinet, how should I attach the countertop? both to the wall and cabinet.
2. How do I install the knee drawer?
3. Should I cut and remove the carpet below the desk cabinet?

Essentially, I have the materials I need but need guidance throught the whole process.
Have you heard the expression "just enough knowledge to be dangerous"? That's me! lol

Thanks
Kat

3. definitely cut out the carpet from under cabinets.
1. Cabinets are usually screwed to the wall at a stud and to each other thru the face frames. How deep is the cabinet?? Countertops are never fastened to the wall, but screwed from under the cabinet into the top. Careful that screws are not too long.
2. Not sure what you mean by a knee drawer. Drawers are usually fastened to cabinets on either side or to the ctop.