Get your best bottle of Liebfraumilch at the ready

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1. Refund = Long legal battle and as you state the company could go bump before you reach the final hurdle.
2. Not sure and don't want advise in case the said Lawyer is crap. There was once a chap called trifonov who used to be on here, although judging by this latest photo he's been eating too much Ready Break and is desperately waiting for the Tie Rack to turn up in Bulgaria:
http://www.trifonov.info/en/index.html
3. Difficult one, if you plough any more money in, best to know for sure that the development is complete, you're in at about 60% of the cost, hence you're in somewhat of a damned if you do, damned if you don't situation. The resale market is flat on its feet though, if you find something in the resale market for anything like the price you're paying on your current apartment (in terms of the final installments you've got left to pay), you've got to ask the question why are you throwing money (ie the remaining installments) at something thats not even complete.
4. Sorry but nil, in fact allowing for your costs, maintenance and utilities, even forgetting furnishing etc you're likely to have to fund it going forward. i.e. net rental = nil, possibly negative.
5. Proceed if you wish but with caution.
6. 'I do not hold insurance', I assume you have no bank guarantee if the developer goes bust, if they go bust chances are you're left with a mess on your hands, I doubt you'll see much if anything back out of the money you'll have invested, the liquidator is the most probably the only person who will be paid, the banks (who have a charge on the property) are most likely to then dump it to get some kind of return (where you are in the equation who knows). Not guaranteed by any means but likely, someone might take over the project and still deal with you on a continuing basis. But times are tough.
7. With or without Platinum, it an extremely tough rental market in Bansko. Don't bank on any income. Any you get is unlikely to even cover you're advertising costs and additional utilities etc.
8. Maintenance varies and depends on size, to tick the property over (without rental) you could be looking at say £500 for maintenance, key holding etc say £300, utilities say £300, taxes say £200. Hence say £1K - £1.5K just to tick the place over, obviously that depends on size etc and ignores interest on borrowings etc. In terms of legal fees or taxes to buy, well assuming VAT is included in the purchase price then you could be looking at buying costs on the property of say 5% (depends on you legal costs), very very rough estimate, ignoring legal cost say 2-3%.
Forget the wine, can't stand the stuff.