Well, before I answer these questions, I will say that the first Anglican church I ever stepped into (actually met in a building owned by the Vineyard Christian Fellowship but they had graciously allowed the Anglican group to meet there; interestingly enough, I had been attending the Vineyard for awhile) was affiliated with the Anglican Church of Kenya. It had split off from the Episcopal Church because of the issues of the ordnation of the gay bishop and an apparent theological liberalism.
Why do (some) such churches seek to be under African juristiction ? I understand the Africans are more conservative and of course still in the denominational community - but what are the practical benefits ?
Has it got anything to do with ‘protecting the liturgy’ or being protected from the local (geographic) bishops theological decrees.
You pretty much hit the nail on the head. In the Anglican Communion/Episcopal Church, we have an
episcopal (who’d have thought that, eh?) form of governance with Apostolic Succession, which means they are very powerful within the Church, especially through Synods and Conventions where major decisions are made. The Presiding Bishop of the Episcopal Church (currently Katharine Jefferts Schori, the first female Presiding Bishop in the Episcopal Church and a bit too much on the liberal side of things for my liking) and the Archbishop of Canterbury (Dr. Rowan Williams) are more akin
primus inter pares among the rest of the bishops in the US Episcopal Church and Anglican Communion respectively. The Archbishop of Canterbury is not a proverbial Anglican Pope and the the Presiding Bishop, although Primate, is not a Patriarch or something.
In some ways, the primary importance of the Archbishop of Canterbury is because Apostolic Succession traces the longest through him back to St. Augustine of Canterubry who was sent by Pope Gregory the Great (it is still said that the Archbishop of Canterbury is enthroned on the Chair of St. Augustine).
By ‘schisming’ from the Episcopal Church and aligning with the Anglican Church of Kenya or one of the other more conservative diocese/Primates, it allows churches/diocese to remain within the Anglican Communion and under recognized Apostolic Succession, yet find a See that is more in line with their theology.
How does being an African affiliated church differ in practise, theology, administration, worship etc from the local church and does this work OK. What are the benefits and any drawbacks and who owns the actual church building ?
It depends on the Province affiliated with. Such things as homosexual clergy are not tolerated and female clergy are allowed or not depending on the See. Whether troublemakers can be excommunicated or not is another issue (it is virtually impossible to get excommunicated from the Episcopal Church). Also, how communion is treated is another issue (I think if someone tried to do a ‘Clown Mass’ that Priest/Bishop might find themselves on the path to excommunication). The theology might differ (more Reformed or ‘Catholic’, etc.).
The administration will be affected because your bishop maybe across the ocean (although, I have heard there have been attempts to get bishops on the American side, but that is difficult because how do you do it without doubling up on diocese?) and the administrative headquarters of the See is across the sea

doh2:
In terms of the building, the church I went to that was affiliated with the ACK had to meet in a Vineyard-owned building.
The long-term disadvantage is that you are heading the Anglican Communion towards a MAJOR schism. After all, the liberalists will remain in their liberal Sees while the conservatives relocate to more conservative Sees and the Archbishop of Canterbury is stuck in the middle. You’re not solving the overarching problem of liberal theology creeping (or, in some case, storming) the Church, merely putting off the potential conflict.