I've done a few construction loans to build spec homes.
First step is to find the land, get a price and some local information about the market in the area.
Then you need the plan for what you will build along with bids from your subs.
You bring all the numbers and comps for the area to your lender and talk it out. Most lenders know what the average price to build is in their area. If you are too low or high, then they wont take you seriously.
I can build a house for under $60 a foot real easy, but the bank expected $70 a foot as the going cost, so I pad my estimates to get that amount, then when I come in way under, they are happy. Works every time.
If they like your proposal, they will order an apraisal of the project. If it's worth more then they are lending, you're in business.
Funds will be made available for each expense when they come due. I bring my bills to the bank, hand them the bill and they put the funds in my account, then I write the check to my sub or supplier.
You pay interest every month on the amount outstanding. Depending on your lender, the financing will last from 6 months to a year. Then you get perminent financing for the amount you borrowed to build your project. Again, terms depend allot on your relationship with your lender.