Until today, I was too busy; was getting only a half hour or so everyday to work on my plug. So today I methodically manually tested it. Suspecting multiple problems was the reason I kept asking all those clarifications, I did have multiple problems!!
1. The multi boot wiki page had a type it has to be 'usb 0:1', not as shown there 'usb0:1'. When I asked my question in a couple of posts ago, I might not have been clear about it; I had other problems that is why I could not find it by simply trying it. [In fact I had post a question about this at the Wiki page about this, yesterday I think.]
2. With the above correction, the boot now succeeds but not every time, from the sdcard in usbslot (w/ adapter). There appears to be some 'mode' type problem or 'timing'. I have a feeling if I simply repeat the same command 3 times (not tried yet) in the multiboot line, it might succeed a lot more frequently.
3. My usb hardrive has not succeeded once yet, I do not not again it is the same type of problem where it might succeed only say once in 10, or the drive is incompatible. When I try to do manually usb start, sometimes it sees two usb devices, some times one ( I have only one), but most time it does not see my drive; but a few times it see the drive. So I surmise, if I keep repeating the command, once in a while the usb drive might work too.
I know that for the linux load there is that delay, I wonder if that delay is effective for the kernel boot too, or even a higher delay is needed when the kernel comes off of the usb drive. [I hope not all got tired of this thread and at least a few people would see the results --- it took a long time of experimentation -- I gave up all tennis watching today