Once you have a clear estimation of expenses associated with losing the current tenant, repairing/improving for a new tenant, leasing fee, vacancy/loss of rent, decide if you’re financially ready to initiate the action which will cause your current paying tenant to move?

From a funding standpoint, you can expect to pay about 2% of the loan amount for a double closing.As far as closing costs, it is important that you have an Escrow agent that is investor-friendly and familiar with the ins and outs of handling a back to back double closing so that it is handled professionally and legally.

I've been looking to master the sub2 method initially until I can move into other aspects of the sale.

While you may administer investments, the time and energy and perhaps legal resources that go into resolving non-performing notes would go beyond the allowable threshold of activity. 

If so, you will typically receive some level of "legal work" as part of the process.

I don't know your local laws, but here in NJ increasing units is very difficult legally.

However, we were informed today that our closing has to be pushed off to a far-off future date (rate will no longer be locked and basically will have to do the financing process again) due to an issue we haven't run into before, but seems simply not legal to us, so we hope we can get some assistance.We only know as much as we have been told, so here we go... the home we are under contract for was sold to the current owners via an owner carry, so the note is held by a private individual (the owner before the current owners).

That's just initial money needed that will dillute your ROI.

@Csilla Veress A couple of books that may help with understanding PV (present value) calculations, as well as note investing in general, are:Invest in Debt by Jimmy NapierPaper Profits by @Joshua Andrews  (my personal favorite)This blog post by @Mike Hartzog may also be helpful:https://www.biggerpockets.com/blogs/5359/41924-doi...PV is the way most note investors do pricing for performing notes, but for non-performing, you'll want to build an ROI calculator as  @Chris Seveney suggested so you can look at various exit scenarios and take into account costs like servicing, legal fees, insurance, etc. 

I want and will be in compliance to the fullest extent of the law, but to be truthfully honest, I dont want to go any further for this particular renter than what I am legally supposed to do and I want to be ready if the late night plumbing call comes and I am on vacation.