You can normally finance 90% of the purchase price for a lot that is in an approved neighborhood.
If you are going to be building on the lot in the future, you may be able to use the equity in the land as a down payment on the construction loan.
After the short period of time of amortization, you may be able to refinance your loan using the equity at lower LTV. The lenders will give out longer term of amortization if LTV is low.
Lot loans generally have a much shorter amortization period than regular home loans. Most lot loans are going to either be 15 years or less, or they are going to be on a balloon payment. A balloon payment is when your loan payment is amortized over a longer period of time than when the loan is due. An example of a balloon payment is when you have a 30/15 mortgage. Your monthly payment is based on a regular 30 year mortgage but at the end of 15 years you either have to refinance or pay the remaining balance in full. Lot loans that have balloons work the same way, however they are generally going to be maybe a 30/3, 30/5, or 30/7 balloon. So the payment will be calculated over a 30 year period of time but the balance will be due in either 3, 5, or 7 years. Also lot loans will usually require a down payment of 20% or more. The down payment requirement varies by lender but 20% is the normal required down payment for a lot loan.