cell phone service and internet in Khartoum

coming to Khartoum in July Protected content want to know about cell service and internet.

phones: was advised to bring over an unlocked GSM 900/ Protected content buy sim cards there. Will I need different cards to call locally and another one for international?
I know nothing about this and am open to all suggestions. Also, approximate charges.

Internet:
How is service in residential area and price? Is bandwidth enough to support video chat to US with Skype? Recommend any companies?
I will be working in private school? Do you know if their internet service is more reliable?

Finally, one last question: does the govt filter or block any sites, especially western, which would require me to subscribe to a VPN?

Thanks much and look forward to your assistance.