Point is you waste time and money.

So there would be minimal cross selling potential, and it wouldn't make sense. 

They are not brokers, they are real estate agents who work for a broker.You wasted their time looking at 10 homes, and then bought one you found elsewhere.

I thought that saying it’s for investment it would not be a problem at least it’s not to waste on junk.

We've decided to list our current home for sale next week as it's appreciated significantly in the 3 years we've been there and it's a ton of wasted space. 

4) Should I ever waste my time with RV stalls (travel trailers), or just focus on residential trailers?

From what you describe, assuming that existing rental income is honestly reported on your tax returns, you should be able to count both rental income from the existing property, and projected rental income from the other units in what you are buying, assuming a local REI-friendly lender with minimal/no overlays (those are the reason why you see conflicting stuff online). 

We bought that loan and got our AOM to the FC attorney in 2 weeks.If you are a small investor and have a competent attorney, you can drastically reduce the timeline to FC because you're minimizing the effects of 2 of the 3 factors. 

Hiring a professional is a waste of your money.

Paying down a rental is a waste of good money.