You need to get an attorney involved for Seller Financed transactions, especially if you have not done this before.  

Also, you can have 2 apts buildings with the same square footage and same materials, but one can cost a lot more than the other because of how they're designed/layed out, so you need someone who has actually built an apt building involved in the design phase.  

They have effectively told you, by hiring the listing agent, that they do not want to be directly involved in negotiations and it won't go over well if you try to contact the seller.

If I decide to go big and add more units then I definitely would need to get an investor involved so that is something to consider.

I agree, if you're ok with leverage and know the risk involved

Does a Title Company, someone who is working for me, has to be involved from the get-go?

Too many variables involved for a simple answer on a forum.What you need is to find an accountant, a permit expediter, possibly an architect and run your questions through them.  

I've noticed that, in reality, while demo expenses are a big part of it, oftentimes people severely underestimate the other costs involved, like getting everything drafted/designed properly and getting every part of the construction permitted by the City.My overall point was that demo costs are more predictable and foreseeable, whereas people that consider demo and rebuilds oftentimes underestimate the other costs involved, which tend to add up to so much upfront cost that demo/rebuild projects end up being a not-so-great investment decision after you crunch all those numbers.  

Ive had my eye out on a few,havent made any calls yet,im really focusing on knowing what im talking about as far as the extensive terms involved with this bussines.

Hey BARRY welcome to the BP community.The resources here for anything involved in RE are very impressive.