Of course if you wanted to start with more hives (a good idea actually), you could put a package in the observation hive and a package in the nuc or the hive at the same time. More redundancy let's you have resources to fall back on when they get into trouble.
Here are some essentials for the beekeeper:
Bee smoker. (most any size will do for a hobbyist but the big ones are easier to keep lit.). Usually bee smoker is made of stainless steel and leather. And most common size is 4*7' and we also have big size Europe and American big size bee smoker.
Veil, jacket, or suit. I would prefer, if I only have one protective suit, to have a full coverall with a zip on veil. That way I can be pretty fearless of the bees. If you make them mad enough, long enough, they will still get in, but that would require quite a bit of time. If you have the money to spare, I'd buy a jacket with a zip on veil besides because it's easier to take on and off, cooler and handier. I like the hooded ones, as opposed to the ones with a helmet. I was paranoid at first of the hood being in contact with my head, but I have three nylon outfits (one jacket and two coveralls), all with hoods, and have never been stung on the back of the head like I expected.
Some kind of hive tool. Any little flat bar will work. One of my all time favorites is a very old light cleaver (the blade is about 1 1/2" wide and 6" long) that I sharpened on the end. I can pry a box apart or scrape things. It doesn't pull nails well and if the prying is really heavy I do worry about breaking it. If you're going to buy one, I really like the Italian Hive tool from Brushy Mt. It has a lift hook on one end and is light and long has a lot of leverage. My next favorite is the Thorne hive tool with a frame lifter and next is Maxant's Frame Lifter hive tool. But I do like the Italian one from Brushy Mt. better.
A bee brush. You can buy one, or if you hunt or have birds you can use a large feather. It has to be a nice stiff quill to do any good. You will need to brush bees off from time to time. In order to harvest, in order to do other manipulations. Shaking can work sometimes, but sometimes you just need a brush. Like when the bees are all clustering on the edge of the hive you can brush them off before you set the next box on top.
These are nice, but not essential, you can do fine without them, but I don't think you will regret buying them.
A spray bottle with light syrup. (2 parts water 1 part syrup)
Tool box. You can put your tools in a five gallon bucket, but if you want a really nice toolbox, We has one that can double as a swarm box, has a place for a hive tool, a frame grip, a smoker, a frame perch and room inside for odds and ends. It makes a nice stool too.
Queen Catcher. The hair clip kind are the nicest ones I've seen you can pick up a queen without hurting her. You still have to be a little careful, but it is designed to not hurt her and to let the workers out. There are times you just need to know where she is while you rearrange things or do a split and then you can release her. This plus a marking tube and a paint pen and you can mark her too.
A Queen Muff. I got one from Brushy Mt. You can catch the queen in the hair clip and put her in the muff and not worry about her flying off.
A frame nailing device. Kingreal is very nice to put wooden frames together. It holds 10 frames in place for you to nail them. It is a little tricky to figure out at first, but it's a real time saver and frustration saver.
A 1/4" crown staple gun and compressor. Everyone who owns a car needs a compressor anyway. The staple gun is under a $100. Walter Kelly has one that is the right size. It will shoot from 1 1/2" to 5/8" staples (which I buy at the local lumber or hardware store). The 1" are perfect for frames. The 1 1/2" are perfect to put boxes together. The 5/8" are nice for when you don't want it to go through a 3/4" board and the 1 1/4" are nice when you don't want to go through two 3/4" boards (like when you put a cleat on for a handle on a homemade box). Then you don't have to pre drill all those holes in the frames. I was a carpenter for years and am pretty good at nailing, but when doing frames I bend as many nails as I don't bend. Half of them are bent and pulled out when nailing by hand. But maybe my problem is I used to "one lick" a 16p nail and I don't have the finesse.
It is nice to have, but for two or three hives, I don't think it's worth the expense unless you find a used one really cheap. Of course you can always keep your eye out for a bargain on a used one.