In Hawaii, that is unusual for a normal sale. I have seen that done with new projects that have a "project" lender or with REOs. The seller must have had a bad experience and just wants a buyer to be prequalified with a lender they trust. If you want the home, I would recommend you go ahead an get prequalified with their lender. You don't have to use their lender - they just want a second opinion.
It depends on a lot of factors. This is what I tell my buyers and sellers here in Hawaii: If its a normal cash sale, it takes about 30 days. If the buyer is getting a loan, allow 45 days.
Short sales can be difficult. It depends on the investor, how many lenders the listing agent has to negotiate with and if the seller has any additional liens on the property that need to be taken care of. I have represented a number of short sale sellers here in Hawaii and I have a 100% success rate.
First of all the listing agent should have asked if you were working with an agent and even if he didn't ask, you should have told the listing agent. Even though you have been working with an agent, you don't have to use that agent especially if you do not feel that the agent is doing what they can for you. Loyalty both ways. If you were happy with your agent and he or she did a lot for you, you should have tried calling him or her again. If your agent is a great agent and worked hard for you - - you just lost him or her a commission that they worked hard for. Not nice.