Flooring Tile - What is the correct action for me to take in tiling my bathroom?

I'm a newish homeowner. I need you to tell me if I'm about to take the correct steps for preparing for tile in my 20 sq ft bathroom.

Info: Home is 1981. Floor is covered in vinyl sheeting. When I pulled off a baseboard and a corner of the vinyl, I found beneath it what appears to be about 3/4th inch particle board over a plywood base. See photo.

Question 1: Am I correct that what I should do to prepare for tiling is to remove the vinyl and the particle boards directly under it, lay (1/4? 1/2?) inch cement backerboard over the plywood, and then tile over that? And will I achieve the correct height?

I want to make sure from experienced people that I'm about to do the right thing. Thank you!

http://i59.photobucket.com/albums/g318/Timber47/P1080340.jpg

Yes, the vinyl and particle board has to go. Hard to tell, but it looks like plank flooring under the particle board. Is that the case?

Thank you. What is the definition of plank flooring?

Plank flooring is individual boards of something like 6-8" in width and 3/4 or more in thickness. It can vary depending on age of the house.

Thanks. It's not plank flooring. It's large panels of plywood.

What's the best way to remove the particleboard? Circular saw and pry bar? And, do you think I should use 1/2 or 1/4 inch cement board given the 3/4 inch height of the particleboard? In other words, how much height does tile typically add?

You can cut it into managable sections and pry it up. Set the saw to a hair more than the thickness of the particle board.

How thick is the plywood subfloor under the particle board? What are you trying to match the height to?

I pulled up the particle board. I bought cement board and cut it to fit. My next questions:

Do I need to put thinset under the cement board or can I just anchor it with backerboard screws? And, how can I find out if the plywood is of a sufficient thickness?

A photo of current progress (cement board is not attached yet - was just checking for fit):

http://i59.photobucket.com/albums/g318/Timber47/2652_840949458474_9375791_56160404_.jpg

All cement boards need to be bedded in thinset, then screwed to the subfloor.

Your subfloor should be a minimum of 5/8" tongue & groove plywood. If you are not sure how thick the plywood is, you can drill a hole in the floor to measure the thickness. If this is a first floor, you may be able to observe markings on the plywood from the basement.