I'd see if you could borrow a FR and find out if it suits before investing your hard earned dough.
You should be able to go for at least 20 seconds before any trailing is visible and you will be surprised at just how much detail you will be able to capture in that short time.
Set your camera to raw and keep shooting until you fill your card, try for at least 70 or 80 images. You might consider turning on the In Camera Noise Reduction. That will save you having to to darks later.
I wouldn't be worried about Flats atm. Focus on capturing your Light frames for now, learning your camera and how it works with your scope. Enjoy this first stage of the learning curve.