The main thing to remember is that VF2 (and VF1 for that matter) is not intended to be a 'short-haul' game; it's meant to be played over several months or even years. Remember also that the goals are simply part of the game - they're not the main reason, and if they were to disappear from the game overnight I, personally, wouldn't worry that much, although the extra cash can be useful. YMMV on that of course; people like different aspects of the game. It is theoretically possible to get all the goals; some are very unlikely to happen but that doesn't mean they won't. For example
'the perfect match' needs you to be very lucky, as well as patient.
Taking the rest of your questions in order,
bugs only appear when it's raining.
Agreed, I get more socks (and wrappers) than dirt spots as well. I'm not really too worried about it, though.
As I said, you're in for the long haul, so the appearance of duplicate collectables is OK by me; they also help to keep the cash coming in, particularly at the start of the game. I wouldn't want to get all the collectables too early as it would take away some of the fun.
Triplets are rare, but not so rare as all that. Look through the forums and you'll see other posters talking about their sets, often with screenshots.
For help with having babies, see
this post (Section A). You might like to read through the rest of that post as you will find a lot of tips, some of which will possibly be helpful.