Best practise to run full crawl and incremental crawl for big content sources in sharepoint 2010 search service

In our sharepoint farm it has 4 big content source web applications around 3 TB of documents and daily users upload documents around 5 - 10,000 documents, and i need to run incremental crawling every day every 30 minutes and full crawling every weekend,
and when i run crawling (full and incremental) for two or content sources i get below error in event viewer

A database error occurred. Source: Microsoft SQL Server Native Client 10.0 Code: 1205 occurred 1 time(s) Description: Transaction (Process ID 202) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.

Context: Application 'SearchApp'

1. is can i create separate search service applications for big content sources is good idea?
2. what is the best practise to run full crawl and incremental crawl like above scenario in our sharepoint farm?

this farm has two separate crawl servers

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adil