Welcome, plenty of assistance available here from most of the folks - apart from me, who's typically more of hinderance than a help.
Anyhow, can't help you with your first request on capacity, wouldn't really know one end of a normal aircooled unit from the other (I'm a watercooled heretic), other than they all look the same.
Re. the gear shifting, assuming that the internals are all good, VW boxes can be typically tricky (not difficult) to set up,and if not setup correctly, will cause all sorts of problems in terms of shifting and especially in relation to 2nd and reverse. Again, assuming that the internals are good, this can normally be fixed by playing around with (sorry, adjusting) the location of the shifter, just a smidgin one way or the other, and there are quite a few threds relating to this activity, so go have a look in the "Trans" section.
A bit more info/photo about the shifter itself would help - standard VW or aftermarket replacement - quickshift, trigger, etc.. as some have particular operational characteristics/traits
You'll also find quite a few threds about bushings - sloppy/worn gear linkage bushings will cause problems, as will poor trans mounts, cracked nose cones, worn hockey sticks etc. As with most cars, the list of problems could be endless, and fixing it could range from a ring spanner and 10-mins of your time, through to a full engine out/trans rebuild - although I'd initially go for the 10-mins/ring spanner solution shifter adjustment solution to start with, I'm very much a "glass half full" kind of fella.
Others will provide you with far more constructive assistance, I'm sure.