I made some test today .
First I have race version of jeatseat it has four independent motors in the seat and 4 motors in tha back grouped two left and two right .
I know that FSE version has opposite direction (four indepentent motors in the back and left or right in the seat) at least it had one year ago when I bought mine .
During the year I had no problems at all with this motor but I do feel a little differences in rumbling force and sound of them but only in the begining of gentle turn .
In hard fighting it's not noticable at all.
I also play in Vr with head seat so differences in sound doesn't matter for me .
And now answering Your questions .
Yes I feel very clear rumbling of all motors in tight turns when plane is coming to its limits and the moment of stall even more (Separate from G-forces which comes from left or right side motors but at 250-270 km/h there is no much G-forces). All eight motors rumbling during stall so there is no information about left or right wing.
When climbing they also give You information but much less noticable (practically only in the moment of stall )
G-forces in turns comes from two left or right motors and back or seat motors during diving or climbing.
In very fast tight turns 500-600 km/h they will give information only from g-forces .Of course more G more rumbling and with visible information like washed colours till full blackout it could be helpfull. This is really nice and add a lot of immersion to the flight but will not give You 100% certainty like during stall.
What about strenght for me motors are ok but it's personal feelings I use about 30-40 of total strenhgt of motors.
Like Alonzo said You don't need any additional sound card
With this new version of Wing there are more effects like gun fire ,damage ,engine beat ,and few others which helps alot and add a lot of imersion to Sturmovik series .
Hope I helped.