Mainly because they know the local market better than anybody else that is not a seasoned investor in the area.

This may not help seasoned investors, but rather, those just starting out with limited cash reserves.

I'm not sure if each building has to be seasoned for two years, or just the investment endeavor.

After a seasoning period of 6-12 months, I then refinance for 60000 for 30 years (or whatever I am getting good cashflow at) and go on. 

You need it off the mls and it may even need some time for seasoning once you pull it off.  

I'm an inexperienced wannabe landlord and want to see what other more seasoned investors do. 

There are a lot of seasoned investors out there in North Jersey.

Looking for one that preferably has little to no seasoning periods for refinancing at a cash-out option.

Depends on the lender you use, some will have seasoning requirements, in this case you would need to hold onto the property for 6 months to a year.

I would keep the term of the loan short as your sale into them with financing allows them to take title and season it while building cash flow and reserves which should allow them to qualify for an institutional loan to take you out.