One thing I do regularly in our Arrow is practise engine out glide approaches. Put youself somewhere near the field and close the throttle at 2000 ft and try and make the runway. Even though I do it regularly its difficult as wind etc makes a big difference. I normally find that I am much better at the second attempt so its good to keep current.
As you say, the Arrow glides like a brick, particularly with full flaps. I therefore always stay high and wait until short final to add the last bit of flap.
I have tried removing the flap when practising glide approaches. I find that reducing from 30 to 20 degrees helps but any more hardly makes any difference, This is why I leave full flap to short final.
If you are on short final, have put in full flap and are low when the engine quits then I would leave the flaps as removing them is one more thing to distract you. This is why I always leave the final bit of flap to as late as possible.
As for the undercarriage I would just leave that down. At 90 kts it doesn't make a huge difference and you will have to hold the automatic retract override which ties up one hand at a busy time. It also takes 20 secs to cycle up and another 20 to come down
All the above would depend on the situation, If I was going to hit a house I might try everything to stretch the glide, however if it just meant landing in a field I'd probably concentrate on doing that well and without injury and let the insurance company take care of the aircraft. One danger with stretching a glide is stall/spin and that could be more serious than the engine failure.
Again, I recomend trying a couple of glide approaches regularly.