I'm useless at harmony so:
What is an inverted perfect cadence? Are there any other variations of cadences like this?

Also if i'm shown a 2nd inversion minor chord, in order to discover that its minor do i just put it back into its root position form so i can see/work out more easily? (same with any other inversion of any kind of chord, that was just an example ie. if it's augmented in root its also an augmented chord if its muddled up into inversions?)

What are errors in voice leading/doubling that I could look out for? (not in my own writing - a question i'm being asked is to find faults in an already written part, not 100% what im looking for)

I think that's all for now

Inverted perfect is where one or more of the chords in the cadence are in an inversion I can't see any problem with putting an inverted chord into root position in order to work out what it is, as long as you remember to write down the inversion as well inverting it doesn't change the actual chord, so there shouldn't be any problem
for the errors in voice leading/doubling, you can have parallel octaves/5ths, chords missing notes, chords in root position doubling the 3rd, hidden 5ths and part crossing i think there are others that were on the first mock that I can't remember though..

hope this is all right, as that's what I've been putting in my papers good luck with the exam!

I imagine an inverted perfect cadence (ie V - I) would have the first chord in an inversion.
ie Chord of G (G at the bottom) followed by C is a Perfect cadence. could an inverted one just have the B or D at the bottom of the first chord ? I know it wouldnt look like a V-I then but I cant think of another explanation.

Second question, yes you could rearrange the notes to see what triad it gives eg (from bottom) Bflat D G then is clearly G Minor, but with Bflat at bottom its a first inversion.
The same could apply to Augmented and Diminished chords
In my Aural at ALCM (many moons ago) the examiner played me E flat G flat, C, to say whether major minor, augmented or diminshed, and what inversion. I had trouble with it. He then played the top two notes, and asked me what interval it was. I correctly said Augmented 4th. So he said only one triad has an Aug 4th at the top. so what is it ? Ah , says I , a Diminished first inversion ! Correct he says. 8/10 for Aural and I squeezed the pass mark.


EDIT, took me while to type that so I hadnt seen Oboe Piano's post when I started it.

Thanks guys Why oh why am i so useless

'Useless' -quite the opposite- because of your question there were some interesting/useful answers!

Strictly speaking, no. Both inversions of an augmented chord sound like augmented chords (exactly so in equal temperament) but e.g. the inversions of C E G# are spelt E G# C and G# C E, each of which has a major third and a diminished fourth adding up to a minor sixth. In an aural exam you would not be expected to know that an augmented chord was inverted.