Your kit should have 2 different packets in the box. One will be a seasoning blend, and the other will be cure ingredients. Use according to the instructions, but it will probably be 1 packet of seasoning and one packet of cure for each pound of meat. Don't mix cure/seasoning together until ready to mix with the meat.
A small kitchen scale should be used if in doubt about the weight of the meat. Also, keep in mind that meats which are thawed after freezing will have some water loss due to the thaw process, so it will weight less than when it was packaged. A slight reduction in meat weight won't adversely effect the product...a large difference will become very salty.
In case the instuctions with the kit doesn't mention it, I recommend curing at least overnight (8 hours)...I prefer a minimum of 24 hours, myself.
With cured meats for jerky, you can smoke and dry at lower temps. Without cure, it is recommended that you raise the internal temperature of the meat over 160* prior to the drying stage...this basically cooks the meat. The texture, color and flavor are dramatically effected by this process.
The reasoning behind the higher initial temps with uncured jerky meats is that any bacteria which could be present in the meat can become heat resistant if the temp is brought up after the drying phase...this is due to the reduced humidity present in the meat. It takes high heat and moisture to kill the bacteria.
As for moisture content of your finished product, the dryer it is, the longer the shelf life without added preservatives. I check the texture by hand prior to pulling from the smoke...I want a leathery feel...pliable, but will tear on the crease after folding in half. This gives alot softer chew, which it sounds like is what your looking for. If hand-slicing, go about 1/4" thickness...this can be done safely if not rushed, and this thickness is harder to overdry than 3/16-1/8" thick.
I store long-term in the freezer in ziploc bags, removing as much air as possible, or vac-sealed bags. I refrigerate for intermediate storage (up to 2 weeks), and less than 1 week at room temp in a closed poly bag.
As for smoking time, I pull the smoke wood after 15-20 minutes...small pieces of meat can take on alot of smoke flavor rather quickly. Then, I finish drying without smoke.
Oh, if cured meat is used, I smoke @ 110-120*, then dry @ 120-150, depending on how loaded my smoker is...heavily crowded jerky requires higher temp for drying due to more meat contributing to the humidity level in the cooking chamber.
Lots of info here...I digressed.
Hope this gets you started on your new adventure!
Good luck on your first jerky run! If done correctly, you'll love the homemade! It's hard to destroy a batch of jerky so don't worry...even if overdried, it's still edible...if you have additional questions, feel free to ask!