Hi and welcome to the Pellet Mill!
I will try and address some of your questions as best I can. First off, the placement of your pellet stove and the air circulation in your home are very important pieces of the puzzle. With proper placement and good air movement you can use a stove rated at a lower btu rating. I am not familiar with the btu ratings of the Englander stove models you mentioned above, but I can tell you how my setup works.
My house is approx. 2400 sqft, 8 rooms, 4 bedrooms, 2-1/2 bath colonial with 2x6 construction and double pane windows, oil fired forced hot air furnace, 2 zones, located in North East, MA. It can get pretty cold here, we've seen -10 here this season.
I recently purchased a Harman P35i insert, whose btu rating is only 35,000. I was concerned that it was probably too small to even heat my downstairs floor, but I have been pleasantly surprised! I installed the stove (which is an insert) in my family room in the fireplace opening. The family room is on the North end of the house, the opposite end of the house from the furnace, has a high ceiling, a drafty fireplace opening, is located over an unheated garage, and has several large windows and a outside door in it. All this added up to making it the coldest room in the house. Fortunately, there is also a 6 foot wide doorway into my large central kitchen just 10 feet from the fireplace, and there is also a ceiling fan in the center of the room.
For the above reasons, I decided that installing an insert in the fireplace opening would be my best option. The insert itself had two advantages... 1) It did not take up any valuable floor space in my room, and 2) it turns a cold drafty fireplace opening into a heat source. I quickly discovered that by turning on the ceiling fan to the medium setting that the room temperature was very consistent from floor to ceiling (usually only about a 2 or 3 degree difference), and the ceiling fan also seems to circulate the air through the 6 foot wide door into my kitchen and throughout the rest of the first floor. I set the ceiling fan to draw the cool air from the floor up to the ceiling and mix it with the warm air. This avoids having a breeze blowing on you, which causes evaporation and makes you feel colder, even when warm air is blowing on you.
I have also found that an effective way to use this setup is to use the oil furnace to heat the first floor zone to a few degrees less than what my target temperature is... say 66 degrees. This only takes a few minutes in the morning and uses very little oil. Then I light the pellet stove and turn the ceiling fan on and then set the thermostat in the first floor zone to 58 degrees. I find that my little 35,000 btu P35i can easily maintain the temperature in the zone and gradually raises it a few degrees in a few hours. The nicest thing is that the family room is now the warmest room in the house, which is nice because this is where we spend most of our time in the evenings.
I keep the doors to the bedrooms upstairs closed in the morning and the thermostat in the upstairs zone set at 58 during the day. When it gets nice and warm on the first floor, I open the door to the master bedroom which is right at the top of the stairs and let the heat begin to drift up there. The oil furnace never fires for the rest of the day on the first floor, and only occasionally fires on the second floor on the coldest of days. I have cut my oil usage by almost half so far this year as compared to last, and have only used 40 bags of pellets so far this season. I turn the stove off when we go to bed and keep the thermostat set to 58 in the downstairs zone. In the morning I give the stove a quick cleaning, let the oil warm it up to 66 and light the pellet stove, then turn the oil back down to 58.
One thing I would caution you against is getting too large of a stove. They tend to burn dirtier on the lower settings. There is definetly a sweet spot and on mine it seems to be an auger setting of between 2 and 3 and the blower on 55% or so. You also don't want to get too small of a stove either, but as you can see from my story here, with proper placement and air circulation (as well as a reasonably tight house) a lower btu rating stove can do a nice job, without cooking you out of the room.
As for the multi fuel stove, just be sure corn or whatever alternate fuel is locally available and makes sense. My stove is a dual fuel wood pellets and corn, but corn is not readily available here, and I have heard it leaves a somewhat sticky residue on the inside of the stove. I can't burn 100% corn either... the manual states it must be a 50/50 mix of corn and wood pellets I believe. Another disadvantage of corn is that it is also a food source, so you need to keep the critters from getting at it.
Hope that helps! Keep us informed on how you make out.