Hi Mead_Monster - and welcome. While I agree with the others who suggest that you need to read (or watch some videos) a little more before embarking on a mead project, as an educator, I think that providing some very basic answers to posed questions is also useful - so to answer one or two
A smack pack - is the name for a particular kind of way that lab cultured yeasts are packaged. To activate the yeast you need to smack the plastic pack with your open hand and that splits open a bag inside the package that provides the yeast cells with the nutrients they need as they rise from their torpor. You still need to add nutrient when the yeast convert sugar into CO2 and alcohol. Honey has virtually none of the critical compounds and minerals the yeast need to transport the sugar in the honey through their cell walls
Sugar break - that is a mead maker's borrowing from a brewer's term called a hot break or cold break. In brewing these refer to objective phenomena where the proteins in the wort collect at specific identifiable and known temperatures. When mead makers refer to a "sugar break" this phenomenon is not so identifiable - in fact it does not really exist but it refers to specific "amounts" of sugar converted by the yeast. One third, would mean that if your starting gravity was 1.090 then the yeast will have eaten their way through 30 points of sugar (the gravity reading would be 1.060. At half break, the gravity reading would be half of what the original reading was (1.045 if the original reading was 1.090. Of course, if your starting gravity was 1.050 or 1.120 then the 1/3 break would be at a different point... There is a practice used by many mead makers (but by no means everyone) to provide the yeast with additions of nutrient at different points in the fermentation process (at different "sugar breaks") . This process is referred to as SNA (staggered nutrient additions). I tend to make low alcohol meads and add all the nutrients at one time shortly after I pitch the yeast. So far, I have never had any problems. But I prefer simplicity rather than complexity.
Yeast CAN eat their way through fermentable sugar quite quickly - seven - 10 days is not uncommon so if you want to catch those so-called sugar breaks you may need to be taking readings every day. Assuming you sanitize your hydrometer and samplng cylinder and whatever tool you use to draw up the sample there is no waste as you can always return the sample to the fermenter.
Temperature is critical. Too high a temperature for the strain of yeast you have chosen and the yeast will be stressed and produce all kinds of unpleasant/undesirable flavors and aromas. Too cold a temperature and the yeast will become sluggish and that will slow down the fermentation and MAY result in undesirable aromas simply sitting on top of the mead unable to be expelled because the yeast is not producing enough CO2 fast enough. Best practice is usually to ferment at the lower end of the yeast's preferred working temperature (see yeast spec sheets).
If you prefer a sweeter mead you have one or two options. One option is to allow the mead to finish bone dry, then you stabilize the mead by mixing two chemicals that then prevent any lingering yeast cells from reproducing and refermenting your mead and then you add some sweetener (could be fruit or honey or sugar or agave or ??? ). A second option is that you add a sugar that is too complex for the yeast to ferment (lactose , for example). A third option involves you working to make a mead whose potential ABV (alcohol by gravity) exceeds the yeast's tolerance for fermentation. By that I mean if your yeast can convert all the honey in a batch to make a mead whose ABV is say, 16% ( a starting gravity of say, 1.125) then you make sure that your must (the solution you are fermenting) has enough honey in it to force the yeast to quit AND still have say 10- 15 points (or more if you prefer the batch to be sweeter) of unfermented honey. The challenge is that most strains of yeast have relatively high tolerance for alcohol so you will be forced to make a mead that is very alcohol rich and alcohol rich wines and meads have their own problems (They can taste unpleasantly "hot", for example, or they can be out of balance with the amount of acidity in the wine so they taste bland and so forth). Moreover, the higher the starting gravity the longer a mead (or wine) takes to be pleasurably drinkable. One other way you can think about producing a sweeter mead without jumping through many hoops is to think about making what is called a braggot - A braggot is beverage made with honey and grain (think ale or beer). Grains contain unfermentable sugars that are perceived as sweet (hence the usual practice today of adding hops to beer and in the past adding gruit herbs - these were to balance the sweetness (typically about 15 points of sugar in each gallon: That's about 6 ounces of sugar in every gallon) although later it was discovered that hops , for example act as a bactericide and allow the beer to have a longer shelf life, among other things).. Braggots CAN be high alcohol but they can be session drinks too ( an ABV of about 5% ) so you can happily quaff 'em by the pint and not sip them by the glass.
All that said, see if you can get hold of Ken Schramm's seminal book on mead making (The Compleat Meadmaker) or Steve Piatz' (IMO) equally good book on the same (The Complete Guide to Mead Making).
Good luck