Putting in new tub and shower kit

I got the same style which it only has one off on handle. Being that this is the same type on there now I'm thinking that we do not need to replace the valve body.
That is if we're lucky enough that the old one matches up to the new one.
Our problem in the past has been getting the old shower arm off. What is the best way to get it off?
Second problem has been getting the old spout off. I fear it breaking and making a big mess.
BTW, It is tiled around the area, going all the way to the ceiling.
There is a closet in the hallway that sits right in front of the tub. I have not seen or noticed an entry to get to the plumping from there.

I know as a rule of thumb you turn right to tighten and left to loosen is this true for these installations?

I ask because I had come across some odd balls that were in reveres.

I'm laying the tile down tommorow and hope to have everything ready for husband to finish off the plumping.

 

Recent valve bodies made by the same manufacturer may allow the same cartridges, but not likely in your case unless the old one is very recent(2-3 yrs). And from the description of how difficult it is to get the old components off, yours is not recent.

If there is no access from behind, but there is a closet, it is fairly easy to cut thru drywall or plaster to gain access. While you have access, if there are not shutoff valves, now is the time to install them. Use 1/4 turn full port ball valves.