They will over the long term increase your monthly profits, not decrease them.  

Hi BP community, I need some serious advise here in a situation in facing with two of my home flips.I've been flipping houses for over 15 years, completed over 50 flips, a few years ago I decided to start buy and hold using the strategic (BRRRR), but I never stop flipping houses, even the profits on the flips is decreasing each year with the high competition when buying  foreclosed properties.Now I'm facing a situation where I have two houses on the market for sale (SFH), the properties are on the market for a couple months and we didn't have any offers yet, if I lower the price I might don't have any profits or maybe 10-20K.

It would blow your mind how many Trumpsters were for a balanced budget and reining in spending but will vote yes for a $160,000,000 bond for construction of a single campus, for a bedroom town with a decreasing student base and with no big industry in the district.  

Some things I would consider is that if you do use them as rentals: -Will the potential wear and tear by tenants significantly decrease the resale value?

You can include your taxes into your rate, but that may decrease your bookings as your comps will most likely be less per night.

The number of units in-and-of-itself would not decrease your cap rate, per se.  

Do you have any thoughts on how you could decrease the your time to find another deal?

That is a huge driver of growth in this area, and if it halts not only the housing values will decrease but it might be hard to find renters if people lose their jobs.

Does it make sense to put down more than the minimum down-payment in order to decrease the P+I and increase cash flow? 

Sure it will decrease cash flow a little bit by refinancing but we will be able to build a lot faster this way.