There are plenty of compnents for the 16, the best of all gauges. Go to Graf and Sons, Mexico, Mo. website. Their 16 gauge Cheddite low-brass hulls are the best on the market, they will last an average of 5 - 7 loadings. Use the Cheddite wads or the Gualandi G-28 wads for 1-ounce loads. I suggest that you stay away form any 16 gauge wad clones, they load u[ my guns with heavy plastic streaks at the muzzle. You can also use the Remington 1 1/8 ounce wads but you will need to insert a 28-gauge OP wad in the cup to keep from having to make any adjustments to your loader. I get mine from Precision, it takes about 1/2 hour to stuff a 250-wad bag of the SP 16s. If you want to use once-fired cases, use the Federal or Estate 16 gauge. The Remington and Winchester cases are not worth picking up. Any primer is okay if you don't try to max out your loads, keep them to 1100-1140 FPS.
I have been loading for the 16 (I have 16 16-gauge guns) for well over 40 years and at present I shoot over 3,000 16 gauge rounds per year, and the best powder I have ever found for the 16 is Solo 1250. I hear it has been discontinued but there is still a lot of it around. I suggest strongly that you do not use Longshot under any circumstances, it is loud, boomy, and dirty in the 16. Ditto Unique. 1250 gives very mild recoil at about 1100 FPS and patterns very well shot sizes from 6 - 9. I use #8s for trap, skeet, doves and wobble, #5 for squirrels and rabbits, and #4 for turkey. I don't have very many opportunities for duck hunting so can't comment on that, but I do use Brenneke 1-ounce slugs in an A-5 that somone had equipped with a scope base. I load #1 buckshot in the 1 1/8 ounce SP 16s when I need buckshot, which is not very often.
There is absolutely no difference in loading the 16 than when loading the 12. I use a Grabber for most of my loading but use my ancient MEC Jr. when experimenting, which is what I do continually.
These recommendations are for modern 16 gauge guns. I have an elderly, 1920s vintage Ithaca SXS that I use frequently for dove and then I reduce my loads to 1000 - 1050 for that gun. I use a Oehler 35 chronograph to determine the speed of all of my concoctions.
I think you will enjoy the 16, it is a very pleasant change from the 12. Un- less you just like recoil in which case I suggest you invest in a box of Rio heavy field loads, they'll tear your arm off.
The Remington Hull will be the one that you can most easily find in once fired condition. Downrange makes a 16ga wad now and that wad in the Remington hull makes a good 7/8oz load with International Clays and a Remington primer. There's been a lot of interest in the 16 over the past 10 years, so now there's a lot more data out there than there was in the past. The best place to find load info is through the website 16ga.com.