Don't plan around or rely on this prospective offer. Continue to apply for other jobs. You may end up with better offers.
If it comes through as expected, great, you can evaluate your options at that point. Until then, you should hope for the best, but plan for the worst, these things can and do get cut off at any time, nothing is final until your first day.
This is indicative of bureaucracy, not bad communication. This advice applies to any kind of business transaction / negotiation like buying a house, car, whatever, talk is good, but it doesn't mean anything and can't be relied upon until its in writing and money changes hands.