Check my PM procedure/math

This was my first PM attempt, please let me know if I did this right or wrong or any other comments. Thanks in advance.

grains: 8 oz crystal 40L, 8 oz carapils, 8 oz munich, 8 oz biscuit = 2 lbs. total

mashed all this together at 150* for 1 hour in 3 qts. water (1.5 qts/lb). Can I mash all the grains together or should the crystal and carapils be done separate? Should I be using more mashable grain next time?

After 1 hr, removed grain bag and sparged with 2 qts of 170* water directly over the pot. Up to 5 qts of wort now. Took out a sample at this point for a hydro reading. It was hell trying to cool that down to take a reading, any suggestions? Hydro reading was about 1.048 at 85*.

Added 4 more qts of water for a total boil volume of 9 qts (2.25 gal). Brought mix to a boil and added 5 lbs. of DME, .75 oz of williamette at 60 min, .50 oz of fuggle at 50 min, .50 oz of fuggle at 30 min. Total boil time of 60 min.

Cooled to 62* and pitched safale S-05 dry. OG was 1.053. After 17 days, FG is 1.013.

Efficiency Estimate:

crystal 40 = .5 lbs x 34 = 17 points
carapils = .5 lbs x 33 = 16.5 points
munich = .5 lbs x 37 = 18.5 points
biscuit = .5 lbs x 36 = 18 points
total = 70 points @ 100% efficiency

1.048 OG adjusted to 1.0447 due to high temperature
1.25 gallons (5 qts) x 44.7 = 55.875 points
55.875/70 = 79.8% efficiency

Could that efficiency be correct? Even adjusting for maybe a higher temp or slightly lower OG, its still around 78%. Could that be correct?

Thanks for any help.

as wort cools it becomes thicker so your 1.048 at 85* is closer to 1.051 at 60*(where most hydro's are calibrated)

other than that it seems a reasonable number