Composite supply of solar system.

Hi,

I need clarification with respect to supply of solar system.
1) A company supplies (composite)solar system @ 5% including installation charges. is it valid? do they require to charge installation charges @ 18% seperately in the invoice.
2) One more clarification required w.r.t to ITC On Travel tickets reimbursement to agent.
An individual books ticket to the company employees and sends summarised
statement to the company for all the bookings made by him at actuals( sometimes charges minimal rate of RS.50 or 100 for some bookings). Can a company take Input tax credit under GST? Or is the company liable to pay GST under RCM Method.?

Awaiting for the early response.. thanks in advance!