Explanation
When you configure an EIGRP summary route, all networks that fall within the range of your summary are suppressed and no longer advertised on the interface. Only the summary route is advertised. But if we want to advertise a network that has been suppressed along with the summary route then we can use leak-map feature. The below commands will fix the configuration in this question:
R1(config)#access-list 1 permit 10.1.1.0 0.0.0.3
R1(config)#route-map Leak-Route permit 10 // this command will also remove the "route_map Leak-Route deny 10" command.
R1(config-route-map)#match ip address 1

Explanation
"Blocking all subnets of 172.16.0.0/16 major network with a mask lower than 23 from coming in" would block 172.16.16.0/20.
The first prefix-list "ip prefix-list PL-1 deny 172.16.0.0/16 le 23" means "all networks that fall within the 172.16.0.0/16 range AND that have a subnet mask of /23 or less" are denied.
The second prefix-list "ip prefix-list PL-1 permit 0.0.0.0/0 le 32" means allows all other prefixes.

Explanation
To configure Spoke to Spoke communication we can configure DMVPN Phase II or Phase III. But in Phase II, the first few packets would go through Hub. In order tototally ignore the hub, we have to use DMVPN Phase III:
DMVPN Phase III is same as Phase 2 but removes some restrictions and complexities of Phase 2. Also allows greater variety of DMVPN network designs we use:+ ip nhrp redirect in hub: tells the initiator spoke to look for a better path to the destination spoke than through the Hub. Upon receiving the NHRP redirect message thespokes communicate with each other over the hub and they have their NHRP replies for the NHRP Resolution Requests that they sent out.+ ip nhrp shortcut in spokes: overwrite the CEF table on the spoke. It basically overrides the next-hop value for a remote spoke network from the default initial hubtunnel IP address to the NHRP resolved remote spoke tunnel IP address)