I am in the initial stages of planning converting my detached over sized 2 car garage ( 30x26, 780sqft ) into an ADU.

 Once a person lets earnest money  go hard, they become emotionally attached.If you find yourself in a situation, where there was something majorly different than what you realized, then it is my firm opinion that it is best to let the seller have your earnest money and take stage left.Remember, no deal is better than a bad deal.No, I have not always been the master of that particular principal.

My plan is to lend my money only at this stage.

You WILL see the data jump and actions happening at each stage.

Agree Sean, I'm in the early stages/data gathering but I do have a business interest in the area now so I'll be there more over the next few months.

I have seen people hiring designers from out of country for around $10/hour then have a handyman assemble and arrange the furniture from pictures which sounds feasible.Any suggestions?

The video and stage guys are heavy on promotion and short on reality.  

We expect to close end of May; and the home is move-in ready (and currently staged). 

At what stage did you buy: in-process rehab or one that had completed rehab and was leased?

During underwriting, preliminary title searches, insurance procurement, and appraisal arrangements are initiated.