Can I assume its a cap lock you have?
As far as shooting aids & acrutiments required. The list is endless. If what your looking at appears to fill a need. My advice: Just buy it.
As far as the rifles put-together. Since its a un-finshed B/P gun. You might consider putting up a pix or two here to show its condition. Then sit back and read what others suggest or needed steps to follow.
Your rifle shouldn't be all that hard to complete. Those kit guns. Most of the hard things to do for the average Joe were resolved prior at the factory.
Missing parts: That may be a issue if aftermarket parts aren't available. Not wanting to infringe on Frontier Gander suggestion. Those missing parts may also be found here:
https://www.trackofthewolf.com/
I have ordered some things for my rifles here & there over the years from Track of the Wolf located in Elk River MN without ever incurring any disappointments. (their a local business here) Great fellows always willing to discuss or pose question too. Anywho. Get that rifle build underway. By or before Fall. You should be familiar with your rifles workings & capability before carrying it afield. After-all B/P deer season is the best time of the year for many of us. Well~~ almost._