I had a similar situation:  did a sub-to by having the seller establish an intervivos revocable trust, with my entity as trustee and the sellers as beneficiary. 

Most of my issues is the money aspect considering I’m 18 I don’t have an established credit so I think my best option would be to find a hard money lender to fund my first duplex.

In my opinion, these are good things assuming you're dealing with someone established and reputable.

This job is typically 100% commission, but being that it is not an entry level position and I am an entry level candidate, they have offered me a decent sized salary to supplement me until I can establish a foundation in my area.

And it delayed closing our loan about 1 month.Now, we use a title company associated with an established law firm. 

We haven't established an LLC but plan to do so once we have a property to put in it. 

To your question though, any bank with experience lending on storage will have established practices for determining value.

Being subject to rules/regulations that the board can change is fine... until it's not. 

If the property is located in a zoning district that does not allow for 3 family use, then look for a document that shows that the property existed as a 3 family PRIOR to the zoning ordinance being established.

This space wouldn't count as a bedroom so you wouldn't rent it out to anyone.It sounds like you live in a heavily regulated state like California where the government constantly tells you how to live.