Q1) Hi SW-28HF is most inaccurate. I put 80 watts peak in and it displays >169. I put 2.8 watts in as a carrier and it reads 5.7 watts. Swr reads wrong too. On a resistive dummy load of 50.9 ohms it reads 1.2 swr. The display sometimes has artifacts until it is powered off and back on.
A1) Please try to set the SW-28 as followings
SW28HF rest data to FW 100 ,RW 100, Then Hold the menu, fast push peak botton 2 times to entre the menu mode 
set the select menu to [FW   set  86 ], select menu to [RW  set  96], long push menu change to" + "or " - "
and then SAVE 

Q2) does SW-HF28 work with this Frequency is 27.385 MHz in SSB mode
A2) It work 27MHz ,AM/FM mode , but not for SSB

Q3) The ref (reflected power) didn’t have a decimal? The fwd displays a decimal?
I’m talking about the digits under the swr, there’s no decimal   So would 1000 equal one watt or ten watts. 0025 equal 1/4 watt?
A3) It has a decimal point, which is at the front, because the reverse power value is measured more finely, so it is placed at the front.

Q4) Can I check the output power without a dummy load?
A4) It need to use a dummy load. Accurate power measurement requires a load. Connecting an antenna also allows power measurement, but requires counting. This is because the SWR must be 1.00 before the value is reached for accurate power measurement.

Q5) What is the battery of SW28?
A4) 502540 3.7V 550mah li-ion battery