My question is about a bit in ROTK when the hobbits are on their way home. I think it might even be before arriving at Rivendell (I'm not sure; I'm at work right now). They've seen Saruman and they're speculating on what's going on at home, and one of them says that Lotho's sure to be behind it, whatever it is. Why Lotho? What's been set up to suggest that, to them or to the reader? Of course they're right, but it looks to me like a glitch. Someone suggested that it was due to the fact of the pipeweed in Isengard, and what they knew of Lotho's character, but frankly I'm not buying it. Lotho can't have been the only source of Longbottom Leaf, surely. And darn it, didn't that happen fast? I mean, unless Saruman was consciously moving against the Shire even before he was demoted, and if so, why? I think it was Farmer Cotton who told them when the trouble started. It gives pelnty of time for the occupation to unfold, but why would Saruman have picked on the Shire for his trade and domination? Was it just because Gandalf liked hobbits? Or because he figured the Shire had something to do with the Ring, either because of Gandalf's interest, or because of some warning from Sauron? (Am I answering my own questions?)
Well, to break your post into two issues- the first one is a bit rickety on Tolkien's part, and suggests psychic powers on Sam's part...
The second, though, is covered pretty well in The Hunt For the Ring etc; and, yes, Saruman's interest in the Shire is in part due to his suspicions raised by Gandalf's interest in the place... but in part also due to Saruman's secret envy of Gandalf, and his surreptitiously taking up smoking in imitation of Big G.
What's not really made clear in THFtR, though, is how Saruman knew that the Ringwraiths were hunting for the Ring when they turned up on his doorstep- or even that the Ring had been found (even if we surmise that, being no dummy, once Saruman cottoned to the Ring's resurfacing he figured out where Gandalf had it stashed).