1) benissimus' answer sheet has 'I determine nothing' is because cernere can also mean 'to determine'. I remember this one confused me too, but it makes sense now (after the wondeful passage of time). benissimus noster a lingua latina in Anglam libere converterat (or something to that effect anyway)
9) at vita illius modi aequi aliquid iucundi atque felicis continet: but the life of those level-mannered men contains something of jocundity and also of luckiness.
The reason iucundi and felicis are in genitive: yes, you're right, it had been so long since I've seen it that I forgot entirely about this construction. vide:
• When a second declension neuter adjective is used, you can convert the second declension neuter adjective into a second declension neuter singular noun, if you put it in the partitive genitive case (G&L p. 235 §369 r.1):
• ‘aliquid bonum’: ‘Something good’
• ‘aliquid bonī’: ‘Something (of the) good’
• ‘aliquid bonī atque memorābilis’: ‘Something (of the) good and (of the) memorable’
• ‘aliquid bonum et memorābile’: ‘Something good and memorable’ (this is better because of the combination of declensions):
NB: G&L p. 235 §369 r.1 says ‘Neuter adjectives of the Second Declension can be treated as substantives in the [partitive] Gen.; not so adjectives of the Third, except in combination with adjectives of the Second, but here usually the Second Declension adjective is attracted’. The ‘attracted’ means: the second declension adjective is brought out of the partitive genitive, and ‘attracted’ to the case of the third declension adjective, which is in the accusative in the above example; so the second declension adjective gets put into the accusative case if there’s also third declension adjective. Of course this is usual, not always.
Hope that didn't confuse you more!!
11) Yes, although you want 'spe' instead of 'spem' (remember carere takes the ablative), and keeping with the sense of the original, you probably want carebant.
12) I don't see why not, but you want to keep your adverbs closer to the verbs their modifying. Still in this case it's an ablative of manner (=adverb), so I really don't see why not.
advenient just means 'arrive' rather than 'come', so again, sure. But there's no context (that's my big gripe with Wheelock, none of that other stuff that everyone else is always complaining about - just the lack of context with the P&Rs, SAs, and Self-Tutorials).
13) In general I think it's better to keep your genitives after what their meant to modify. Poets don't though I hear, so why should we?
I don't know the answer to this one, but I'd think that yup, puts too much stress on the neighbour, not enough on his house (context dependent though)
14) est is definately necessary for the perfect tense (otherwise people'd think you were using oppressus as just an adjective rather than a verb - A&G says that verbs in the perfect passive system aren't considered periphrastics, even though that's what they technically are since it's 2 words performing the function of one).
I wonder if the poets remove their ests from their perfect passives? I guess I'll have to wait a couple of years (till my latin's done and gone good) to find out.
You'll have to wait for someone else to respond too with better suggestions. It looks to me like yer alright. I had very much trouble at first with participles being in the same case as their nouns, but now it seems very obvious.