Is hard money the way to go or should I be looking into a conventional loan? 

One of the banks offers a "business entity loan" product for LLCs that buy 1 to 4 family investment properties.  20% down, 30 year fixed conventional mortgage at 5.25%, with a personal guaranty by me and my husband who are the only members of the LLC.  

Specifically relating to 2-4 unit multi-family buildings, is it conventional practice for the owner to simply pay for water, sewer, and trash or is it conventional practice to bill these expenses back to tenants? 

No one charges that little. 

As I work everything out there are still some questions that I prefer not to get from Google.Is there an initial fee management companies charge new clients with preexisting properties besides the monthly percentage to manage them when starting new business?

If it’s a 3/2, why not get 2 roommates and charge them at least $400?

I can offer 10% down with seller financing with a 15 year term and a buy out clause (as described in the calculator) or take out a conventional mortgage with 10% down.

Charging an application fee and then stating that it's non-refundable are two great ways to pre-screen applicants.

Do a conventional deal with a realtor at both ends-yours and the sellers.

then go with hard money......here is what i see conventional mortgage from a bank 5% for 25 years closing costs around 1-2 points.