Jack
If the unit has it's own fuel pump as noted in Jim's article, I have no idea why they'd suggest yet another one.
If the second tap is indeed useful, by all means use it (read the literature / manual for the unit to assure yourself that this is actually how it is designed to work). You're right about the fuel filter change, but that was discussed earlier. Based on Ken Heyman and Ron Hill, need for bleeding the fuel lines is significantly reduced if you fill up the filter with fuel or injector cleaner. When I did ours the last time I used the injector cleaner, the only thing I needed to do was twist the knurled knob twice to get the engine to start, so there was a minimum of air in the lines. But there was some, so learning to bleed both the engine AND the new heater is a good thing to know.
I was kidding (a little bit) about the heater / generator thing. If we do ever buy a generator, it'll be the 2000 for the reasons you mention. We keep a good electrical system going with a 360 ah house bank and new 100 A alternator and Max Charge regulator, so we have more than two nights on the hook without having to run the engine, but hot water for showers is nice, especially when it's cooler outside.
Your DIY approach is very good, because that way you'll know everything about the new system. Good luck, take some pictures and write it up for Tech Notes.
There's not much more that I think Jim could add to his well written and documented article.