Tile/Cement board removal

Id just like a little confirmation before I demo my bathroom. The current tile floor has loose tiles. A few cracked ones as well. It is laid over cement board, screwed to 3/4" OSB on second floor.
Im assuming that if I want to replace the tile floor, it is necessary to remove the tile and cement board? What is the best way to do this? Was thinking flat shovel, pry bar, maybe a shingle remover/roofing shovel? Should I expect the screws to rip through the cement board and stay secured in the OSB?
After demo, was going to replace the cement board and lay 13" porcelain tile with the highest quality fortified mortor I can find. Suggestions?

The current tile floor has loose tiles. A few cracked ones as well.

These are symptoms of a greater issue. Wouldn't be wise to re-tile without first getting to the bottom of the problem.

Im assuming that if I want to replace the tile floor, it is necessary to remove the tile and cement board?

That is correct.

What is the best way to do this? Was thinking flat shovel, pry bar, maybe a shingle remover/roofing shovel

There is no "best way". You are on the right tack and basically doing what I would do. If it got tuff I would bring out the ole trusty chipping hammer.

Should I expect the screws to rip through the cement board and stay secured in the OSB?

Yup, you should. After the board is out the screws can be broken off at the surface then hammered down.

After demo, was going to replace the cement board and lay 13" porcelain tile with the highest quality fortified mortor I can find.

High quality high dollar mortar isn't necessary. You do need to determine why the original floor is in the condition it is in.

Suggestions?

Add another 1/2" layer of exterior grade plywood underlayment (Exposure 1).

These are symptoms of a greater issue. Wouldn't be wise to re-tile without first getting to the bottom of the problem.

Keeping what Bud said in mind as you demo, look for some of these specific errors, and take and post photos also:

Grout at the perimeter of the walls

Little thinset coverage under the tiles or tiles coming loose with there being little bond to either the tile or to the cement board

Cement board panels not being taped at the seams with mesh tape

No thinset under the cement board or construction adhesive used under the panels.

Once the subfloor is cleaned up, if the subfloor panels are not gapped, it's an install error or if you can slide a putty knife straight through, it means they aren't tongue and groove subfloor panels. You also didn't mention the age of the house, and if it's planking under the cement board, that would cause your problems also.

Let's help you get to the cause before you put one bit of new anything back onto that floor.

Thanks for the replys' guys. The house was built in '01. Ive removed one cracked tile and can tell you that it was poorly bonded. Also, the cement board under that tile is flexing, up and down if that makes sense.

Are you supposed to place thinset under the cement board? Wounldn't screws suffice?

What about this product I saw at HD today? Some sorta rolled out material thats' supposed to take the place of backer board. Was called Easybond something or other. Expensive stuff.

Don't use Easybond. Yes thinset is supposed to be installed under the cement board.

Add 1/2" ply, then Ditra.

Easy Mat.