Hi,
A qualified yes to both.
As the battery reaches 85% state of charge it will taper the acceptance rate to about 12.5 amps per hour (per 100 amp-hours of bank). Increasing voltage will merely take the battery above the "gassing" voltage (which is temperature dependent), so "smashing" the battery with higher and higher voltage doesn't do a heck of a lot for charging.
The other reason MPPT is good is as temperatures rise panel voltage falls. But it takes a LOT more heat for a 24 volt panel to drop below 14.8 than it does a 17 volt panel.
No matter whether you go PWM or MPPT insist on a temperature probe for the battery bank. That will idealize the charging voltage.
