Well, first, $625k is a long ways off from $750k. How motivated are they? Are they selling $750k on the open market? If so, you can work their number down by pointing out that your offer doesn't include $45k in commissions, you will close quickly, etc. But your price is still a ways off from their amount. Your 17% away from their desired sale price.
Item 2 above is just them financing the sale, basically them becoming a bank. You give them $10k and they carry a note for the rest. Note terms can vary, but a standard one is 5% interest, 30 year amortized payment, 5 year balloon. Every one differs. Since you are not going hard money, paying points and interest only, etc., option 2 allows you to offer them more. but with this option, I feel you would still be below what they could get on the open market.
Item 3 is just a lease option. You acquire the home, they hold a lease option contract with you. This is good because you don't have to get financing, it is attractive to a rehabber, etc. They would typically need to be a motivated seller for this to work, but every seller has their pain points and motivation points.
The items above are just my thoughts, not knowing what the property is worth, condition, etc.