What should be the thought processes for a startup after receiving approval. To build a team of web engineers first and then select a technology stack or other way round? 


Building a team of web engineers should be based on technology stack. Going with hiring first approach, you may ended up selecting  stack that may not serve intended purpose and may result into founder developer gap. Hire a consulting CTO first who should be able to set a bigger picture. 

The best option would be to follow below three steps.
1) Get onboard consulting CTO.
2) Each startup is trying to solve a unique problem, consulting CTO should help you do due diligence along with  
    other stake holders and should come up with a technology stack that will address unique problem efficiently.
3) Start hiring star team member that fits your technology stack.