It will improve your chances in the sense that US medical schools flat out do not accept degrees earned in countries other than the US or Canada.
Will it improve your chances significantly?
Considering that only about 15-20 non-Canadian international students were accepted at all US medical schools combined last year–not really.
Not if you find a medical residency in the US and later find employment as a physician in the US–but that’s becoming extremely difficult. Most residency program will not sponsor visas for international students due to expense and legal headaches of sponsorship. Those that do sponsor visas typically only sponsor J-1 visas–which means you may not be allowed to remain in the US after you complete residency.
But getting the private loan is the hard part—you will need a qualified US citizen or US permanent resident to co-sign any private loan.