3. Is there a ban on corporate donations to political parties?

Election Campaign Finance Act 2013 -Kenya (Section 15)
15. Support by an organisation
(1) Any person who, or an organisation which contributes to a candidate, a
political party or a referendum committee shall channel such contributions through
the expenditure accounts specified under sections 7, 8, 9 and 10.
 

Political Parties Act, s 27
The sources of other funds for a political party are—
(b) voluntary contributions from a lawful source;
(c) donations, bequests and grants from any other lawful source, not being from a non-citizen, foreign government, inter-governmental or non-governmental organisation; 

Organizations (including corporations) are allowed to support candidates and parties but have to follow strict guidelines.

Importantly, an organisation is defined by Section 2 of the Election Campaign Finance Act to "include a club, group, foundation, business or a registered society."