Hello Prabhu,
Question 1: See the data rate section of the AP7632 data sheet.
Data Rates Supported 802.11b/g: 1,2,5.5,11,6,9,12,18,24,36,48 and 54 Mbps; 802.11a: 6,9,12,18,24,36,48, and 54 Mbps; 802.11n: MCS 0-15 up to 300 Mbps; 802.11ac on 2G VHT MCS0-9 up to 400Mbps, 802.11ac on 5G: VHT MCS 0-9 up to 867 Mbps
Question 2: The AP7632 can manage up to 64 like model APs (AP76XX).