How to properly create and configure SharePoint 2013 Search service with PowerShell?

Question

Hello Forum,
I have installed SharePoint 2013 across three tier servers:
WFE Server  (Of course, SharePoint is installed here. Bsically this is just a Web server)
APP Server  (Of course, SharePoint is installed here + Central Admin + Service Apps).
SQL Server  
I now want to create and configure the Search service, obviously on the APP Server, But of course the search functionality should work correctly on the WFE server to.
I want to do this via a proper PowerShell script. I found Spence Harbar's script on: (http://www.harbar.net/articles/sp2013mt.aspx), But it has three problems, and they are as follows:
1) Spence Harbar himself literally stated on his article that this script is for: "deploying on a single server farm", But what if I have three tier servers? Could anyone please help me out in suggesting the required tweaks in the
script?
2) By default Search uses the SP_Farm account, So, How can I change the script to use other dedicated account for the search service e.g. SP_SearchAcc ?
3) How can I modify the script to specify a default Search center?
4) Apart from all the three aforementioned point - Is the script missing anything? 
I would greatly appreciate your inputs - Thanks !

Answer 1

the only differences are where you place the components.  if you are doing a small server farm with a 1-1-1, most likely you just need to change the script so that you set the index and query processing component on the front end, but the others on
the app server.  just a 2 second update... just keep in mind this will work, but I am making several assumptions without any knowledge of your farm, users, capabilities. 
generally, there would be more of a breakout on the topology than that, but im guessing for this farm that you wont have dedicated search servers.  also, a lot depends on # users (rps really), # items in index, size of VMs (RAM for query processing,
Disk for index, etc, etc), and making sure the topology works for your particular environment and needs. 
if you want more detailed topology help, which aligns as closely as possible to "best practices" (not that those exist in SharePoint, go ahead and provide the total # users, average/peak RPS for search, current index size, content source types,
VM specs RAM, CPU, #/Size of drives, HA concerns/priority (obviously isn't, since only 1-1-1)
Christopher Webb | MCM: SharePoint 2010 | MCSM: SharePoint Charter | MCT | http://christophermichaelwebb.com