You have asked help on the entire gamut of HR function. What is left out now? Almost nothing. Against this background, I recommend you hiring HR consultant.
Secondly, if yours is just a start up, then why you wanted to do so many things at a time? Let HR evolve as the company evolves. At this stage, the most important thing for you is establishment of Performance Management System (PMS). If you do that then you will have PMS based recruitment, employee training, rewards, promotions, salary increase and so on. What PMS does is to lay the foundation. Therefore, concentrate on building the foundation first. Structure can be built later. If you wish to refer my earlier post on PMS, then you click the following link:
Management Training Consultant
2nd June 2015 From India, Bangalore
4th June 2015 From India, Mumbai