I've been learning a lot from this site, but this is the first time I'm posting. I have a couple questions related to a job in my home that I'm going to do. I have not done any work on it yet, but I'm trying to plan this all out so I can do quality work and do it quickly. I'm going to be redoing all the DWV for 1 Lav, 1 Bathtub, 1 Kitchen Sink (excluding existing in-wall galv drain/vent), and 1 WC (replacing all cast-iron up to foundation with ABS). The plan is to remove the lead-oakum from the bell of a CI pipe that runs into the concrete foundation in the crawlspace, then attach ABS from there using a donut.

1. For the rough inspection, I understand that I'm supposed to fill up the plumbing I do with water to the roof. For this, I'm planning on inserting those screw-type test caps on the sinks, toilet flange and tub trap arm. However, I'm a little worried how I prepare the ABS to CI interface. Do I cut the ABS and put a test cap on the ABS pipe that will go into the CI bell? Then how do I reattach it after the test?

2. I have about 10" that I can use to slope the pipe for all of this (including fittings). The current CI work is back-graded so it's pooling at the cleanout so I'm trying to partially redesign the existing work so that I can correct the grade. I know that horizontal pipe is supposed to run at .25"/ft but can it slope more if necessary - without going vertical so I don't have to use big fittings - for a short run so that I can match it up with the CI bell? For example, a couple 45 Deg elbows on the "horizontal".