Or attorney?

I have had better luck with having an attorney sign the security deposit letter, it may cost you a little more up front but it beats the alternative.

Do you have Power of Attorney? 

Since this is my first time seeing this and I havent even had a chance to build a buyer's list, get a title company or find a real estate attorney, I'm like a deer in the headlights right now.

Since this is my first time seeing this and I havent even had a chance to build a buyer's list, get a title company or find a real estate attorney, I'm like a deer in the headlights right now.

So I don’t think you will be able to have one signor on the mortgage unless you build a relationship and history with the lenderYou should seek an attorney to discuss asset protection with properties and ownership. 

A lot of questions here...As your dad has a 50% interest, and a trust owns the other 50% of which you and your two siblings are the sole beneficiaries (I presume), it might be advisable to, after the trust interest is distributed, to have your father, you, and your siblings contribute your interests to an LLC in exchange for shares of the LLC (usually called "units").The property would be re-titled in the name of the LLC and the LLC can use it as collateral for a loan.It's usually highly advisable to engage an attorney to draft an operating agreement in this scenario to get everyone on the same page about ownership interest, who is/are the managing member(s), what happens when someone wants to sell -- do the existing members get 'right of first refusal', what happens if a member passes away, etc.

The lease to own agreement went terribly wrong when it was drawn up by the tenants attorney and clearly geared to benefit the tenant.

Did you consult with an attorney or use any other resources?

Did you consult with an attorney or use any other resources?