I am remodeling a bathroom in my 1928 tudor home built ona pier and beam foundation. The original bath layout was not thoroughly designed...the bathroom door opens into the toilet and the shower door opens into a large pedestal sink. Since the bathroom is torn apart for the remodel, I thought I would improve the layout. As such, I have several questions on waste/vent plumbing for the proposed configuration. Specifically around moving the toilet drain location 5-6 feet from the existing position. First a few diagrams/images for illustration:

Figure 1: Original and Proposed Layouts


Figure 2: Exposed Wall with Notes


Figure 3: Crawlspace Plumbing Reference



Plan/Questions
My plan is to cut the cast iron arm (D in figure 3) and attach a pvc sanitary elbow (via mission coupler) to run a new 5-6 foot pvc drain line to the new proposed toilet drain location. I would like to splice the sink into this same drain line. My questions are:

1) Do I need to run a new vent for the toilet? Most reading I have come across states that additional venting is needed with the critical distance exceed 6 feet (see example in figure 4). However, I had a plumber tell me this weekend that plumbers (at least in Texas) are adopting/following a new international standard for critical distances and that I could get away with 10 feet. Does this sound right?

Figure 4: Typical Critical Distance Diagram


2) If I do need a new vent for the toilet, can I create an auxiliary vent off the new drain line such as depicted in figure 4?

3) Can the sink splice into the same drain line the toilet will use as long as that splice extends upwards in no less than 45 degrees from the drain line?