No, the RT 175 is a 2 stroke.
Two Stroke.
175/150
I think it will. If you look at biebandit.com and find the oem Yamaha parts for the motorcycles in question and check to see if they are the same part number, if they are then they will interchange. you can crosscheck different years too if you found a 1975 ty 175 cylinder for your 1975 dt 175. So check out bikebandit and see for yourself, they are the next best thing to a Yamaha dealer.
Yamaha IT 125, 175.
600cc
6.8:1
440 cc
396 pounds
$1000
Yes it is
One can use a Yamaha PSR 175 for a computer. Keyboard a required for a computer. Also, one can purchase the keyboard for a very cheap price at Staples.