(a) Is it usual in this economy for suppliers of goods or services to supply those goods or services to corporations on credit?

Yes.

(b) If so, what would be the average credit period of time?

60 days to 90 days.

(c) Is it possible and/or usual in this economy for a supplier to require security over property of the corporation for the supply of goods or services?

It is possible but not usual.

(d) If so, is the form of supply known as 'retention of title' practised and recognised in this economy and is it enforced?

Yes. Retention of title is common in lease transactions.