customize openvpn core for use custom cryptography algorithm

[r0otsharp]

hello there

i want to customization openvpn core with bellow features:
1) can i customize openvpn for set cryptography algorithm for some client in one instance OpenVPN server???
2) can i customize openvpn for works when server ping(icmp) port is blocked??
3) can i customize openvpn for automatically switch other server when the main server is down. i means load balancing in other slave servers.
Best Regards
Ehsan Farahani