I have an hour in a Cessna 152, and probably a thousand across various flight sims, and I can say that while the flight dynamics in ArmA are closer than other joint arms sims, they are still very far off (limited rudder and tailrotor authority, power loss when making small turns).
You WILL have to use the keys at some point, such as rolling over 45 degrees. But practice with the mouse first. It's quite easy.
Hmm, a fellow Flight-Sim member! Nice. Got at least 800 hrs in the PMDG 737-800, plus lord knows what in other planes and helos in that program.
I do stand by my assertion that mouse and keys, while do-able, is not optimal in any fashion for ArmA flying. You just run into the limits of that control system too fast. A snap-roll is trivial with a joystick, not so easy with a mouse. Keys alone aren't precise enough to maintain a good lock during a dog-fight and you rapidly run out of fingers to hit keybinds with.
A vanilla Logitech joystick is not that expensive if you are already buying laser mice. The better stuff cost more of course. But I can merge my various controllers by CH Products into one virtual mega-controller with adjustable response curves. That allows me to get more oomph in handling just where I need it.
Also, I rarely fly a airframe with engines at 100%, leave some room in the throttle to boost power lost by turns and climbs. That's basic combat pilot technique.
Please practice in places other than public servers. I recently witnessed a person jump into a Chinook on an ACE Domination server and promptly flipped the chopper over during take-off - killing about 8 players in the process. No one yelled at the guy, but it was clear that he was not qualified to operate that aircraft and never should gotten near the pilot's seat at that point.