I realize money is tight. But don't give a newbie a POS to learn on. Sujecting them to malfunctions and non standard sights & magazines release & grip safeties, et al...is asking for trouble.
As for caliber, .22LR or 9mm.
During the War, everyone just assumed Pappy Boyington flew the best F4U in the squadron. In his book he said different. He said he flew the worst of the bunch so as to give the less experienced pilots a equipment edge in the sky. NRA pistol training in Texas isn't the same has fighting aircraft pilots of Japan's Imperial Navy over the Pacific. But I hope you under the meaning. Good Luck.