My ‘standard’ 32 caliber squirrel load in my Pedersoli Scout flint (and percussion, I have both locks) is 12-15 grains of 3F Swiss. An inch high at 25 yards, about an inch low at 50. Use a Ballistic Products 1-1/2 buckshot and a wet patch, with a .375” hard felt wad (Duro-Felt Products) over the powder. I’ve standardize on 3F Swiss for most of my shooting, but 4F shows a lot of promise in 32 caliber. No reason to think 2F powder won’t work, though it might be a bit slower as a pan powder if you are shooting flint. You won’t know until you try it.
The only conicals I have tried much in the 32 caliber Scout were some semi wad cutters dropped out of a Saeco mold that weighed in at around 100 grains. Played with sizing and paperpatching, but other than perfectly round holes in paper targets from semi wad cutter design, found no advantage and soon abandoned the idea.
As far as max charge, a 32 caliber muzzleloader is not going to be a ‘magnum’ no matter how you load it. Think of it more in terms of a 22 rimfire that delivers it’s 43 to 44 grain bullet pre expanded to 32 caliber. All I’ve found with heavier loads is more fouling and loss of accuracy. I use the dry felt wad between the powder and patched ball because I have found a wet patch can mess with the rather small 12-15 grain powder charge, but will let you load and shoot all day.