MySql Cluster transaction Performance

I'd appreciate any help/suggestions you people working with MySql
cluster can offer.
I'm hoping MySql Cluster can help us with a high volume need.

Our needs are (at max load) 10M Million inserts per hour. Each record
is narrow (20 columns mostly numeric).
We then update those 10M records...running some simple math
calculations.
We then categorize them (another update pass)
We then insert them to Sybase db
I can then delete these records and get on to the next customers (which
have been streaming in the meantime).

I'm thinking Solaris 9 on v440. 16GB Ram.
4 servers (ndb nodes)

What is the best config?
I know there are issues on replicas and fragments that help in that
decision.
Is 2 replicas @ 2 fragments ok...how many replicas are enough...how
many fragments?
What questions do I ask to help make that decision?

Perhaps something like this would work?
Server #1. Mgmt Server
MySql Server
NDB Node
Server #2 MySql Server
NDB Node
Server #3 NDB Node
Server #4 NDB Node

What transaction activity numbers can I expect?

Can a 4node v440 with 16GB ram handle such volume?...are there rules of
thumb for such calculations?
Perhaps I don'd need a 440...and something less will do...again what
goes into that calculation?

This is (I think) high volume. 21M inserts/hr, 20M updates/hr. I wonder
how failsafe MySql Cluster is and what if any additional steps I need
to add.
Should I be thinking about writing data to disk for persistence
protection?
Is that within Cluster setting I should be using or via some external
method?
What is the recovery time bringing on down/back online a node?...lets
say with 8GB data)

Best location to store that persistent data (local disk raid 5 or raid
10 or SAN )...what questions answers help me with that decision?

I expect you who have used Clustering will have quick rule of thumb
answers or issues I also need to consider so I'd like to hear from
you.

Many thanks.
David