So many of your questions are answered in the sticky at the top of this forum that it seems strange that you claim to have read it. I assume in all this that you are considering a OneWorld Explorer ticket (this being just one of many types of RTW ticket).
1 In principle they all look doable, although some of the sectors you show would require 2 flights (this isn't a problem so long as you stay under 20 flights in total ad 4 per continet (6 in North America). There's no problem going East or West within travel regions (basically the world is in 3 regions: The Americas, EMEA, Asia & SW Pacific) provided that you only enter each continent once and cross each of the Pacific and the Atlantic once. Personally I find Westbound a bit easier on the jetlag.
2. You are allowed four flights in each continent (6 in N America) - except the continent of origin (which would be North America the way you have these currently) where you are only allowed 2 stops (but still up to you limit of flights if you wish.
3. See above - 4 stops per continent not 2. Obviously you can do separate side-journeys using other tickets or other modes of transport.
4. Yes you can. Market economics, supply & demand, and all that.
5. You would need to reroute the ticket at a cost of US$125 (possibly plus a service fee of US$30-50 depending on who does the reroute).
Can I suggest you have another careful reread of the sticky in this forum?