Saaaaaaaaweeeeet.
You have a lot of good stuff to work with.
The shocker girder.....nice.
Full front brake....nice.
Not a fan of the comstar wheel, but is a good strong unit.
Disc brake conversion using the more powerful front type caliper.
The engine looks to be a 1600 dual port. It should have the good fan, fan housing and the good oil cooler. Also dual oil control pistons. This would be the engine to have. All the aftermarket parts are made for this engine.
I can not see much of the trans in the pics, but it looks like it may me the only piece from a 1200 beetle. It looks like a short axle swing to me. The gearing will be lower than you want......put tall tires on it to make up for such low gearing.
Your specific questions.
You are pointing at the axle seals. There is a normal lip seal there, but also several gaskets and O-rings. Someone has put a disc brake kit on it. So all those parts listed above have been apart. If not replaced (dont come with kit) and/or assembled wrong, then the axles will leak gear oil.
Now add the disc brake bracket......many many of the cheaper kits do not fit well. The bracket you install most often are not the same thickness as the drum brake part you remove. This makes for multiple shimming/endplay problems that you must overcome. If yours is a short axle swing you definitely will have these mods/adjustments to do. The later model trans (IRS and later non usa swing) they are a direct bolt on.
Now to add to the conversion process the replacement seal kits dont fit well. Mostly the O-rings tend to be too thin. You must make sure the O-rings not just go over the shaft but that they are fat enough to crush tight in the chamfer when axle nut is tightened.
Now the axle nut must be extremely tight or the O-rings will leak. Somewhere in the 265 ft lb range.
Next on the steering neck.
IF it is a harley based neck the stem will be a solid 1 inch shaft and can be cut and re-threaded to make shorter.
IF it is a Jap bike neck it will be thin and hollow with a taper. Different top and bottom bearings. They can be shortened, but is more difficult with fine metric threads and a lot of measuring to know that you will not be too thin. And the stem will likely need lathing for the shoulder the bearing fits.