There are better trainers out than the P-51 PTS..the landing gear is weak...on any trainer a weak gear is a disaster as the student learns to land...I've taught with the Mustang PTS...I have 2 friends with the P-51..I've seen guys at the LHS returning the PTS all had broken main gear...
Yes you can learn/teach on a P-51 PTS..if you can get it to fly you can teach with a brick..won't be easy and it'll take longer..doesn't make a brick a good trainer....
bottom line here is that tankie1rtr is getting started...go to your local field..alot of clubs have a club trainer plane..perhaps you can get a flight in...