@Account Closed Congrats for taking action. In some respects, this is a "fake it til you make it" business - figure out the next step and take action before going beyond that. However, you are also dealing with people in some tough situations with probably the biggest asset they own. You owe it to them to treat them with respect and integrity. If you don't know an answer to a question, don't make it up. Be honest with them about your intentions (you don't have to use the word "wholesale", but you need to explain that you have partners/investors/etc that will close on the deal, not you, and they have to agree with your assumptions and numbers).
That said, to answer your specific questions...
1. In the TREC contract, the option period is your out clause. Generally a 7-10 day option for $100 is acceptable, but you can negotiate whatever you want. You need EMD to make it a valid contract. It does not need to be notarized. In Texas, contracts are assignable unless they specifically say they aren't.
2. Technically the seller will always get cash at the closing table regardless of the source of the funds. Generally when you advertise this you are saying you will close in cash or hard money (i.e. not go through a 30-60 day financing process where the bank has endless opportunity to kill the deal). If you intend to get conventional financing, don't advertise you can pay cash.
3. You need a separate assignment agreement signed by you and the end buyer.
4. You should be paid out of the closing funds by the title company.
I would highly encourage you to find a mentor in your area for your first few deals. There are wholesalers literally everywhere in DFW. First things first though - find a deal. If you think you've found a deal, run it by your mentor and make sure it's a deal before putting it under contract. If at that point you don't have a mentor, PM me with the details and I can at least try to point you in the right direction. I am in Dallas, but fairly familiar with Arlington area.