If the airline goes bust before the MPL is issued, you will get a CPL/IR. So you must still pay to upgrade to a frozen ATPL, and no job guarantee.
Depends if the airline has an agreement with the FTO to fund the conversion. Good question to ask at the interview!
How employable are you with an ATPL gained from an ATPL + 1500 hours. Specifically, how employable compared to someone who trained for an ATPL the conventional way, who has also been employed for ~2 years (i.e. similar training cost, training time, time employed and hours logged)?
Depends on the employer. If you have to embark on a P2F TR to get a job with a new operator, then as long as you have the cash, they will want you, after all they can 'drop' you after line training should an 'unforseen crm or training issue' raise its head. They've got your money, you have the TR, but alas no job.
If an operator actually gives a damn who they employ and has rigourous standards, then the licence should make no difference. It will be you as a person and your competencies and traits they will be interested in. ie you as a person and operator. Number of hours maybe, depending on what they specify. A CAA issued licence is a CAA issued licence. If you can achieve the demanding starndards set out by the CAA to achieve your licence and TR, there should be no difference.