I'm a medical instrument technician currently working for Roche Diagnostics and living in the Fox Lake IL area.

HELOCs should also be considered short-term instruments because they usually have a balloon payment. 

I do want to make sure here . . wouldn't the fact of it showing up on your credit report depend entirely on whether they have recorded the debt instrument? 

You could also look into some passive instrument like a Delaware Statutory Trust as a back up that move a little bit more slowly and provide steady but very unsexy income. 

If let's say I buy and hold this apartment for next 10 to 15 years and sell, do you think it is a good investment (equity + cash flow) compared to investing in REITs or other stock market instruments?

You can get by with a "lite" agreement initially, but in order for most title companies to distribute the funds to your private money partners upon sale or refinance there will need to be some sort of recorded debt instrument (like a simple mortgage or lien stating the terms). 

@Joseph Helms Congratulations on utilizing HELOC as an instrument for financing.

The two actions that were most instrumental in our growth were:1) Selecting full featured property management software with our first purchase so that we could focus on our processes.2) Developing a working relationship with a local portfolio lender that specialized in regional multi-family so that we could avoid issues with DTI.

@Todd Mathisthere are other options like 203k loans etc. i will say hard money will be your best and easiest bet, most likely. i have used it many times and it was instrumental for me.

The lien instrument (deed of trust or mortgage depending on state) will be recorded, and the original promissory note and any other disclosures will be sent to the lender, and once the lien instrument is recorded the lender will also be sent the original.