RE: 2-stroke or 4-stroke?
I just put together a Kadet Senior with a Magnum .91 and it flies great. I am very rarely above 1/4 throttle and I think I have too much engine, especially for a beginner. I did that because I wanted to fly at a low throttle setting for noise reduction, (long story).
I think a 4-stroke, (this is my first one), is just as easy to use as my 2 strokes. Also, although the Kadet will fly nicely with a .46LA, most of the people I know have larger engines in theirs as well. Talk it over with your instructor before you make a decision.
That plane will want to stay in the air if you can't get your engine tuned to run at a low idle, it's like the wings are filled with helium or something.
I know it is more likely that a beginner, ( I am a beginner too, on my 4th plane and seeking an R/C addict's 12 step program), WILL crash at some point but, I really think you would have to almost 'try' to crash this plane once you are soloed and off the buddy-box. Mistakes can and do happen to seasoned flyers as well.
As for 'Engines to avoid'...I know there are probably a few, but most engines will run reliably as long as you care for them and break them in properly. I get sick of hearing guys say...'I'll never buy another____ engine'. It's usually the guy who runs too lean, never bothered to break it in and likes to run 20% nitro at full throttle barely controlling his plane....(No, I'm not bitter...why do you ask?).
I think you will find Magnums to be good engines for the money and you will need to learn about 4-strokes at some point. Just be prepared, as we all must be, to lose your investment. Some of the old-timers at my field say that the only plane that will never crash is the one never flown.
Go fly your plane with full knowledge of the risks invoved and ASK YOUR INSTRUCTOR. He/she will have at least met you and be able to tell better than we can wether you are going to be safe with ANY engine in ANY plane. My instructor has predicted, accurately, which students will be able to learn and which will not. (That is, before they give-up and get an R/C car or truck). No offense intended to those who choose surface R/C vehicles, our club happens to have a full-blown R/C race track and holds regular events.
HAVE FUN!!