Dracula/Headscratchers

Ok, in the novel it's implied that Renfield ONLY eats his prey alive.
It's also implied that he doesn't eat them right away but saves them for later. I can see how this would work for sparrows, and maybe spiders. But how does he preserve the flies?
 * Well, he was catching them using sugar.
 * That doesn't answer my question. I know how he was catching them but how was he preserving them? its implied that he saves them for later but he couldn't keep them for more then 24 hours without them dying.
 * Why can't he? As long as they're still hanging about his cell, there will be more and more flies and thus lives. They needn't be the same flies.
 * As I remember it he was feeding the flies to the spiders so as to concentrate the life essence.

I'm confused about the effect sunlight has on vampires' shapeshifting abilities.
When Van Helsing explains that vampires can't change their form when the sun is up, does he mean that the sun causes Shapeshifter Mode Lock, trapping the vampire in whatever form they were in at the time, or that the sun triggers Shapeshifter Default Form, returning the vampire to human form?
 * It's more like the latter. During the day, Dracula is just like any human, except if I remember correctly he keeps his Super Strength. However he can't change his form at all during the day.

The fact that the novel is composed almost entirely of journal entries, while awesome in its own right, seems to stretch the suspension of disbelief a little TOO much sometimes.
First, how are these people able to recall entire conversations verbatim, regardless of whether or not the conversations took place just before they started writing the entry? Human recollection can't be THAT accurate...
 * That's a trope common to ALL Epistolary Novels; it's a side-effect of the medium itself. Mr. Lockwood, Nellie Dean, Gilbert Markham, Robert Walton, and others all share the Harkers' iron-clad memory. Willing Suspension of Disbelief. Now, if some author in the future wanted to deconstruct this and show what the authors' recollections of past events would realistically look like, that would certainly be interesting...

Second, it's an automatic spoiler, in that when the characters are embarking on something dangerous or terrifying, you know at least whoever is writing the current entry made it out alive and with their mental faculties intact enough to write a journal entry.
 * We can still be surprised in other ways. For example, we knew the first time we read it that Mina Harker survived but not that Quincey Morris didn't. Actually, we only know that the person survived the events chronicled in the entry we're currently reading; until it's the last entry, we never know which entry up ahead will tell us of someone else's death besides that author.

Third, what's with the written stuttering? One character chokes up at the end of one of the entries, but s-stuttering t-typically isn't s-something you *write* down. And there's a part where Mina hesitates, triple-dots and all, to write the word "Vampire". When a person hesitates to write something, they stop their hand for a moment; they don't express the hesitation in the actual writing. I can't help but be reminded of the Monty Python line "Well, if he was dying, he wouldn't have bothered to write 'aaaAAAuuUGH', he'd just say it!"
 * But what we're reading aren't the original handwritten entries, as Jonathan laments at the end; they're Mina's typewritten transcripts. While typing the part where she remembered how she hesitated to write the word "vampire," she could have added ellipses to capture the effect. Also, Dr. Seward recorded his spoken diary on a phonograph, complete with pauses and stutterings that Mina had to translate into print somehow. She had to (well, she at least wanted to) express the act of hesitation within the limits of the print medium. If I were writing about a conversation I had with someone and remembered them or myself stuttering, I would indicate so in my writing, too.
 * Creative nonfiction can explain the dramatic use of ellipses. And from reading first hand accounts from the Edwardian era, people back then really did write like that. If someone talked funny, they damn well wanted to record it for future embarrassment. Also, ellipses were used as a writing trope in journals to pass over unmentionable things. In many WWI narratives, ellipses are used to pass over sources of intense trauma.
 * Also, in my personal diary, I do use ellipses from time to time to convey that I'm hesitant or uncertain about something. When I reread my diary in the future, I want my future self to remember that uncertainty. Would Mina have done the same thing? Maybe not. But it's not impossible.
 * Have fun imagining Mina transcribing the account of her husband's seduction by female vampires from shorthand.


 * For what it's worth, Fred Saberhagen's The Dracula Tape kind of plays with the questions raised by the OP; Dracula himself often notes at times that he suspects that a bit of Unreliable Narrator was at work to make various parties sound better than they were, and it's revealed that several of the entries were concocted by Dracula and the entry-writer (who, unknown to the others, he'd won over to sympathise with him) to throw the others off the scent, and some of the more dramatic flourishes were thrown in because neither was exactly a master storyteller; the others were just too blinkered to notice. In either case, the entries are unrealistically detailed because the writer was at times essentially making shit up.

Which year this novel is set in? And what are exactly the boxes in Dracula's house?

 * The boxes are the easiest question to answer. They are boxes of earth as Dracula must sleep in the soil of his homeland/original grave/consecrated earth. The year is a bit trickier as the dates and information can be VERY contradictory. Popular speculation suggests either 1890, 1893, or 1888. the first for the simple reason that the afterword of the novel states "seven years later". Implying that the events happenex around seven years before. The second is gathered from at least two different instances of the novel. One in which a date is given as a Tuesday and another where Van Helsing laments the death of a felow physican named Charcot who died in that year. The last one is often an attempt at working with the first one and linking the events of the novel of that of the Whitechapel murders.
 * Based on Alan Moore, the events happened about a year ago (i.e, 1897).
 * Various scholars (notably Leonard Wolf and Elizabeth Miller) have looked at this problem, even checking dates against the phases of the moon mentioned in the book, and no answer emerges as entirely satisfying. One may speculate that this wasn't something Stoker cared that much about, and in Victorian literature it's not unusual for works to lack such specifics.