Replacing drain assembly and trap under bathtub/shower combo

[alppolarbear]

I've recently had a few leaks originating in our tub/shower trap and the drain assembly. I solved the trap leak, but am not a fan of the existing trap to begin with. To fix the drain assembly leak, it's hard to get up close with the existing trap in the way. Long story short, I'd like to replace the entire drain assembly and existing trap.

Existing setup can be seen here:

As you can see in the next picture, the excessive amount of caulk did not stop the leak (it's actually on the backside in this picture), so I'd like to replace the drain assembly as well:

The existing trap then drains to the waste line, which appears to be 2" PVC (at work so I can't measure for you until tonight):

What I'd like to do is replace the entire drain assembly, something simple like this should do the trick: http://www.homedepot.com/p/Watts-1-1-2-in-White-Plastic-Bath-Drain-Kit-Chrome-Trim-5CP/100677379?N=5yc1vZc6arZbwo5n

I'm in Massachusetts, so the plumbing code here says a tub with shower head only needs a 1-1/2" trap: http://www.mass.gov/ocabr/licensee/dpl-boards/pl/regulations/rules-and-regs/248-cmr-1000.html#10.08

I have a few questions about this project and would welcome any additional insights you all have to provide.

1) What type of piping is ideal for this situation? This area is readily accessible, as the tub/shower is on the first floor, but can be accessed through moving one of the panels of the drop ceiling in the basement. We also have a cutout in the bathroom closet, that provides access to where the top section of the drain is (where you flip the tab to close or open the drain).
With that kind of access in mind, I'd love to be able to use the compression fitting style pipe, but is that necessarily up to code? Or am I forced into the glued-together PVC piping? I also have hesitations with compression fittings because of the risk of a hot shower causing leaks...

2) The drain assemblies that I'm seeing online mostly appear to be of the 1-1/2" pipe variety. Should I try to find something that is 2" throughout to make the connection to the 2" waste line easier? Do these exist? Is it easy enough to connect the 1-1/2" to the 2" waste line? Suggestions welcome here...

3) Removal of the existing trap looks straight forward on the connection to the drain, just loosen the white nut. What about the waste line side? Not sure how that comes off - again I'm at work now and can't play around with things yet. It looks like I can unscrew the copper/brass/whatever metal that is from the waste line and be able to reuse the existing fitting on the waste line.

4) I've done typical homeowner-type plumbing before, but am by no means an expert. How difficult of a job does this look like?

Thanks in advance!!

 

[phishfood]

This drain or similar http://www.homedepot.com/p/Watts-Schedule-40-PVC-Bath-Drain-Kit-436CP/100679024?N=5yc1vZc6arZ1z11s2y with an 1 1/2" sanitary tee.

Use this trap with a 2" x 1 1/2" bushing in the inlet to hook up the tub drain.
http://www.homedepot.com/p/NIBCO-2-in-PVC-DWV-Hub-x-Hub-P-Trap-C4895HD2/100342771 Since you can access the trap, being able to remove it to snake out the line is nice. If the horizontal drain line is 2", keep the trap 2", as it will drain a little faster, clog up with hair a little less, and is easier to get a snake through.

 

[alppolarbear]

Following up on this. I was able to rip everything out and replace with a conventional p-trap. See picture below.

I ended up having to go with a 1-1/2" p-trap, then convert up to connect to the 2" waste line. We couldn't find all the necessary parts to go 2" throughout. Connecting from the 2" to the 1-1/2" drain assembly was the sticking point. Those 1-1/2" drain assemblies are of the compression variety, and aren't truly 1-1/2" - you could stick the pipe pieces from those INSIDE of a 1-1/2" PVC.

Went with PVC cement on every connection, aside from connecting the 1-1/2" vertical from the p-trap to the drain assembly and the threaded connection to the waste line. PVC cement was a heck of a lot easier to work with than I thought it was going to be, so happy I got that experience.

 

[havasu]

Really a great, clean job!